Dissertations / Theses on the topic 'Earthquake geology and paleoseismology'

In this thesis a paleoseismological off-fault research, consisting in the analysis and dating of seismogeological effects triggered by both historical and paleo- earthquakes (seismites), was performed. Off-fault paleoseismology results particularly useful in areas, like Sicily, where the seismogenic sources are scantly defined and so they can't be directly investigated by onfault researches. Indeed, even if this study does not provide precise and direct information on the seismogenic fault and the earthquake parameters (magnitude, intensity, fault length and elapsed time), however, it can supply useful information on the epicentral distance of the site where the effects developed, the earthquake magnitude threshold and the intensity reached at the site. Moreover, the finding of structures dated before the historical records can be useful to extend the seismic catalogues back in time. Sicily was affected by strong earthquakes among the most disastrous of the seismic Italian history, with intensity Io up to XI (MCS) and equivalent moment magnitude Mw up to 7 (CPTI04, Working Group 2004). The northeastern sector was destroyed by the 1908 Messina Strait earthquake and also suffered for seismic events located in southern Calabria, such as the 1783 seismic sequence. The southeastern sector was hit by the 1169 and the January 11th 1693 earthquakes and by other minor, however damaging, events such as the 1542 one. Western Sicily suffered a destructive seismic sequence started on January 13th 1968. Nevertheless, the seismogenic sources of these earthquakes are not well constrained because they occurred in pre-instrumental time and without clear evidence of surface faulting. Recently, different seismogenic source models have been proposed on the basis of geological and geomorphological evidences, historical and instrumental seismicity data and macroseismic intensity analyses, but the debate is still opened. However, these strong earthquakes triggered several geological effects described by the historical accounts, such as landslides, liquefactions, ground deformations and fracturing, hydrological anomalies and tsunamis characterized by waves that damaged the cities along the eastern coast of Sicily. Then, given its critic seismicity and its millenary historical memory, Sicily is an optimal laboratory to test different paleoseimological off fault methods. This work was undertaken with the main aim on a side of providing new and useful data to better define the eastern Sicily seismicity, on the other side to test original multidisciplinary approaches in a region where this kind of investigations are scarce. Indeed, off-fault paleoseismology is a young and yet few tested discipline of Earthquake Geology. For this reason there is not a unique technique of investigation, instead methods need severe testing and systematization and every study case requires a specific approach related to the site conditions and to the seismite typology. The performed research follows two different main lines: first the examination of the regional seismicity and of the historical accounts has been performed; then a multi-theme research was carried out in field to investigate directly the seismites. The Italian historical bibliography reporting seismogeological effects in Sicily (original sources and previous seismic catalogues) has been analyzed. Descriptions of effects such as landslides, ground deformations, liquefactions, hydrological anomalies have been collected in a georeferenziated database embodying all the information about the causative event, as well. Interactive maps of effects distribution have been realized by the use of Gis software. These data have been also used to define empirical relationships between earthquake parameters (intensity and magnitude) and epicentral distance of the sites where the effects occurred. Then, upper bound-curves, at regional scale, have been realized. This step of the research highlighted that Sicily is a region highly prone to the seismogeological effect development, especially as it regards landslides and ground deformations, mainly clustered in the eastern flank of Mt. Etna and in the northern sector of the region characterized by critical geological and structural setting. Whereas, liquefactions and hydrological anomalies occurred more numerous in areas with specific geological and hydrological features (Belice Valley and Catania Plain). Upper bound-curve graphs also showed that seismic parameters of some events could be misinterpreted, such as the magnitude of the 1823 earthquake (M = 5.87) that could be underestimated, while the new value proposed in the literature (M = 6.7) seems to be more plausible. The same analysisindicated the happening of possible site amplifications and/or exceptional site response during some events as showed by effects occurred at unexpected long epicentral distance at Messina during the 1783 earthquake and at Calatafimi (Trapani) for the 1693 event. Off-fault paleoseimological field study was focused to the finding and examination of liquefaction- induced deformations and tsunami deposits, because their investigation in field results easier than other effects. Indeed, liquefaction structures and tsunamiites remain in the sedimentary sequence as marker of seismicity and tsunami inundations; they have well defined features and take place in areas with specific characteristics, easily recognizable after geological and geomorphological surveys. On the contrary, for instance, hydrological anomalies are transitory phenomena and seismic landslides are not well differentiable from no seismic ones. Hence, after a critical examination of the historical data indicating the localities where these effects occurred during past earthquakes, fluvial and coastal areas of eastern Sicily have been chosen. A further selection was performed using satellite imagines and aerial photos and by geological and geomorphological field surveys, aimed to define the most prone areas. In three sites (Minissale, Agnone and Vendicari) field study allowed to investigate deformational patterns linked to liquefaction mechanism. In other sites (Augusta, Pantano Morghella, Capo Campolato, Vendicari and San Lorenzo) probable tsunami deposits, both sand and boulder accumulations, were found. As it regards the examination of deformational pattern, the detailed investigation of their features and a paleo-environmental reconstruction have been performed to exclude other possible causative mechanisms different from the seismic one. In general, the method for distinguishing subsequent events is based on stratigraphic criteria and cross-cutting relationships. When possible radiocarbon dating has been carried out, on charcoals and bulks, to constrain the age of the structures and to associate them with historical or paleoearthquakes. At Minissale (eastern flank of Mt. Etna, central eastern Sicily) and Agnone (Catania Plain, central eastern Sicily) liquefaction structures have been detected on two artificial trench walls. In these sites a preliminary hand-auger coring campaign was also performedto characterize the stratigraphic sequence and to qualitatively evaluate the terrain liquefaction susceptibility. Then, the deformational patterns, consisting of lateral spreading, dikes, faults, drag folds, recumbent folds, sheet slumps, warped top levels and boudinage, have been studied by the square division method. Terrain samples have been collected for sedimentological and micro-paleontological investigations. Paleo-environmental reconstruction allowed to exclude other causative mechanisms and to associate these deformations to seismic shaking. Radiocarbon dating, combined with the upper bound curves, allowed to associate the seismites detected at Minissale site with the 1169 and 1693 earthquakes and those of the Agnone site with the 1542 and 1693 earthquakes. At Vendicari (southeastern Sicily) a singular association of structures, affecting terrains since Pliocene up to Quaternary age, has been detected. Besides soft sediment deformations (autoclastic breccias, diapyr-like injections and thyxotropic wedges), probably linked to liquefaction mechanisms, brittle deformations, consisting of fractures generally opened and filled by sediments (sedimentary dykes) have been found. Fractures have been examined by a mesostructural investigation and the detailed observation under the microscope of filling material thin sections, as well, to highlight possible relationships with the regional stress field. After a critical analysis of the forms and the paleo-environmental reconstruction, seismic shaking was proposed as the most probable cause of the deformation development. Fractures could be also linked to the regional tectonics characterized by an almost NW-SE trending' 1. The overall investigation of seismites at Vendicari highlighted at least four triggering seismic events, whose age is not precisely constrained given the lack of datable material. However, their finding mark that these events had magnitude greater than 5.0 and intensity greater than IX, that are the threshold values for which this pattern can trigger in the epicentral area. The tsunamiite study was undertaken both searching anomalous sandy deposits and examining boulder accumulations along the southeastern coast of Sicily, inland and offshore. This research required a multi-theme approach combining geological, geomorphological, paleontological, X-ray, petro-chemical, morphoscopic and magnetic examinations. Geophysical applications, analysing sonar chirp profiles, were a preciousinstrument to find deposits off-shore. In some cases wave transport equations were used jointly with statistical analysis in order to determine the extreme events' geological or meteorological' responsible for the deposition. At Augusta and Pantano Morghella (southeastern Sicily) anomalous sandy layers, whose analysis highlighted a tsunamigenic origin, were found into a fine sedimentary sequence. Augusta site probably recorded tree events inland but, given their old interval age, no correlation can be made with the historical record. Only the more recent level could be tentatively related to the 365 AD Crete tsunami. Eleven anomalous layers have been also found off-shore thanks to the geophysical investigation of sonar chirp profiles. The age of some of these layers well matches with some disastrous tsunamis that hit eastern Sicily in historical time (such as the 1169, the 1693 and the 1908 events) and with that coming from Eastern Mediterranean such as the 365 AD Crete tsunami and the event of Santorini (about 3600 BP). At Pantano Morghella three anomalous levels were found. Deep investigations on one of the layers highlighted that it can be ascribed to a tsunami and in particular to the 365 AD Crete one. Further investigations and dating are in progress to understand the tsunamigenic origin and to constrain the age of the further two levels. Boulder accumulations at Capo Campolato, Vendicari and San Lorenzo, were studied with the aim to distinguish if they were deposited by storm waves or tsunamis. This analysis showed that strong storms occurring in the Ionian Sea are capable to emplace large boulders on the coast but up to a given distance from the shoreline. Indeed, boulders very far from the shore seem to require more energetic waves, with periods longer than that of known storms, to be deposited. These waves could be extraordinary unknown storm waves or tsunamis. Dating on some very far boulders highlighted the occurrence of at least two different probable tsunami inundations. The first event could correspond to the 1169, the 1542 or the 1693 tsunami, the second inundation can be ascribed to the 1693 or the 1908 tsunami. The following research allowed to find evidences of both historical and paleoearthquakes and tsunamis in field. Results confirm the potentiality and usefulness of thepaleoseismological off- fault methods and their integration with further information, provided by ulterior studies, should help to better define the seismicity of Sicily. This thesis is divided in seven chapters. First a general definition of the geologic and tectonic setting of Sicily and of the seismic source models, proposed for the strongest earthquakes, are exposed (Chapter 1). Then, a brief treatise on paleoseismology and the investigation methods is provided (Chapters 2 and 3). Performed researches are discussed separately for each different approach, exposing methods and results in the Chapters 4, 5 and 6. Finally, in the Chapter 7 a summary and a discussion on the main matters of this thesis, the applicability and usefulness of this kind of researches are exposed, arguing on how they can contribute to the improving of the knowledge of the eastern Sicily seismicity.

Thesis (Ph. D.)--University of California, Riverside, 2009.
Includes abstract. Includes bibliographical references (leaves 112-120). Issued in print and online. Available via ProQuest Digital Dissertations.

We studied a paleoseismic trench that was excavated across the Banning strand of the San Andreas Fault by Petra Geosciences (33.9172°, -116.538°). The trench exposed a ~40 m wide fault zone in interbedded alluvial sand gravel, silt and clay deposits. We present the first paleoseismic record for the Banning strand of the southern San Andreas Fault. The most recent event occurred sometime between 730 and 950 cal BP, potentially coincident with rupture of the San Gorgonio Pass thrust. We interpret that five earthquakes have occurred since 3.3-2.5 ka and eight earthquakes have likely occurred since 7.1-5.7 ka. It is possible that additional events may have occurred without being recognized, especially in the deeper section the stratigraphy, which was not fully exposed across the fault zone. We calculate an average recurrence interval of 380 - 640 yrs based on four complete earthquake cycles between earthquakes 1 and 5. The average recurrence interval is thus equivalent to or less than the elapsed time since the most recent event on the Banning strand. The recurrence interval is similar to the San Gorgonio Pass (450-1850 years) but longer than that for the Mission Creek strand (~220 years).

La faille Nord-Anatolienne est une faille décrochante dextre de 1500 km et la frontière de plaque entre l’Anatolie au sud et l’Eurasie au nord. Le mouvement vers l’Ouest de l’Anatolie par rapport à l’Eurasie à une vitesse de 21 mm/an est accommodé par le jeu de cette faille. Durant le 20ième siècle, cette faille a rompu d’est en ouest lors d’une séquence de larges tremblements de terre qui ont eu lieu à intervalles rapprochés. De nombreux géologues ont cherché à mieux comprendre l’histoire récente de cette faille, et plus parti-culièrement son histoire sismique ou paléosismologique. La recherche en paléosismologie consiste à contraindre en utilisant l’enregistrement sédimentaire existant la nature et la distribution des tremblements de terre passés. Dans cette thèse, j’ai effectué 4 investi-gations paléosismologiques le long de la faille Nord-Anatolienne dans des lieux où à chaque tremblement de terre la faille forme des escarpements à contre-pente et constitue un piège à sédiment. En étudiant la composition et la distribution des sols enfouis et ex-posés dans de larges tranchées creusées au travers de ces pièges sédimentaires, on peut identifier des « horizons sismiques » (c’est-à-dire la surface terrestre lors du séisme). En datant par le radiocarbone les matériaux déposés au-dessous (avant) et au-dessus (après) d’un horizon sismique, on peut contraindre à quel moment un paléoséisme a eu lieu. Fi-nalement dans cette thèse, j’ai compilé une base de donnée des chronologies de l’ensemble de paléoséismes documentés sur la faille Nord-Anatolienne. Grâce à cette base de données, j’ai pu déterminer l’occurrence des séismes avec une méthodologie cohérente, et analyser la chronologie obtenue à la fois qualitativement et quantitativement. L’analyse des données révèle que la faille Nord-Anatolienne ne rompt habituellement pas en cascade comme durant le 20ième siècle, et que l’activité de la faille est fortement influencé par les trois principaux régimes tectoniques existant en Turquie. Les variabilités d’activité le long de la faille pourraient résulter de contraintes normales à la faille, qui décroissent d’une façon générale de l’Est vers l’Ouest. Une décroissance des contraintes normales à la faille diminuerait localement le seuil de contrainte requis pour déclencher un séisme. Ceci explique l’observation que le temps de récurrence des séismes est plus court à l’Ouest. A l’Est, les ruptures sont plus variables, et le temps de récurrence est bimodal. Ceci peut être lié à des variations temporelles des contraintes normales à la faille, peut-être induites par le jeu sismique des failles Est-Anatolienne et de la Mer Morte.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished

The Eastern Betics Shear Zone (EBSZ) is one of the most active fault systems in SE Spain. It has caused damaging earthquakes in historical times, including the 2011 Lorca earthquake, which evidenced that the regional hazard estimations needed revision. In this context, the available fault data is usually too local and, for some faults, reliable and representative parameters are still lacking. Such heterogeneity has usually hampered seismic hazard models based on geological data. This thesis aims to be a comprehensive study allowing to: i) complete the paleoseismic record and parameters of one of the most active faults in the EBSZ, the Alhama de Murcia Fault (AMF), and ii) include fault data in a probabilistic seismic hazard assessment (PSHA). The study is thus divided in two main parts. (A) a local study presenting a structural characterization and integral paleoseismic study in four sites across a complete transect of the AMF. (B) a regional fault-based PSHA of the EBSZ with the main faults as inputs to define complex fault rupture scenarios using the SHERIFS code. A) The structural characterization has been carried out in the two central segments of the AMF, Lorca-Totana and Totana-Alhama. In the former, five fault branches are identified with partitioning of the deformation. From N to S: N1-AMF (lateral), N2a and b-AMF (dip slip), S-AMF (lateral) and F-AMF (dip slip). The Totana-Alhama segment shows more diffuse deformation, where the most prominent structure is the Amarguillo Fault (AF), a N-S transtensional ramification. The paleoseismic survey has been carried out in eight paleoseismic trenches across four fault branches of the Lorca-Totana segment. We obtained one of the completest paleoearthquake records in Iberia with seventeen events for the last ~100 ka in S-AMF. The recurrence varies from 5.7±1.7 to 3.1±1.4 kyr for the last 73-18 ka in S-AMF and F-AMF. The time compatibility of the last five events in these branches suggests that they could rupture synchronously. The total net slip rate of the segment since 18 ka is 1.55 +0.14/-0.18 mm/yr, considerably higher than previous estimations. The slip rate evolution shows fluctuations over time (super-cycles), some of which coincide with patterns identified in nearby faults, inferring possible activity synchronicities. B) The fault-based PSHA suggests that multi-fault ruptures involving lengths of single to several whole faults of the EBSZ are feasible, contrary to the rupture of the whole system (~400 km). The hazard shows a clear control of the EBSZ faults, increasing the accelerations close to their traces with respect to area source PSHAs. The seismic hazard is dependent on the slip rates, as lower slip rate faults (Palomares fault; PF, or NE end of AMF) have negligible contribution. Our results for the 475-year return period are also more consistent with the accelerations reached in the 2011 Lorca event than the building code or national hazard map. For some faults, the lack of detailed paleoseismic studies can compromise the reliability of the hazard. This is a key discussion in the present study, marking the need for better constrained and reliable slip rates in the EBSZ. The integral paleoseismic study of the AMF has revealed to be a crucial step towards a more representative characterization of its paleoseismic parameters (slip rates, recurrence), and thus, of the EBSZ. Acquiring refined and reviewed paleoseismic data is key to improve seismic hazard evaluations. Hereby, further research should focus on poorly researched faults and on performing integrative studies in other EBSZ faults. The comprehensive approach followed, from paleoseismic data collection to PSHA, contributes to perform more critical interpretations of the seismic hazard, and aims to serve as a case example for other low-to-moderate seismicity regions.
La Zona de Cisalla de les Bètiques Orientals (ZCBO) és un dels sistemes de falles més actius del SE d’Espanya. Malgrat això, en aquesta zona les estimacions de perillositat sísmica rarament utilitzen dades de falles degut a que aquestes son sovint massa locals i poc acotades. En aquest context, la present tesi pretén ser un estudi exhaustiu que A) completi el registre paleosísmic i la representativitat dels paràmetres sísmics de la falla d’Alhama de Murcia (FAM), una de les més actives de la ZCBO, i B) porti a terme una avaluació probabilista de la perillositat sísmica (PSHA) de la ZCBO basada en dades geològiques de falles. A) La caracterització de la FAM ha permès obtenir dades paleosísmiques en quatre de cinc branques de falla que conformen un transsecte gairebé complet del segment central (Lorca- Totana). S’ha identificat un dels registres paleosísmics més complets de la Península Ibèrica amb disset paleoterratrèmols pels últims 100 ka. La recurrència d’aquests varia de 5.7±1.7 a 3.1±1.4 ka pels últims 73-18 ka i la seva compatibilitat temporal entre branques suggereix que les ruptures conjuntes son factibles. La velocitat de desplaçament neta total és de 1.55 +0.14/-0.18 mm/any pels últims 18 ka, malgrat aquesta ha presentat variacions cícliques almenys des del Pleistocè Superior també observades en d’altres falles de la ZCBO. B) El PSHA suggereix que les ruptures multi-falla que impliquen longituds d’una o varies falles completes son factibles a la ZCBO. En base a això, l’anàlisi portat a terme indica que les falles de la ZCBO dominen la perillositat a les àrees properes, incrementant considerablement els valors d’acceleració respecte a estudis previs que no consideren falles. Tot i això, les acceleracions son altament dependents de la velocitat de desplaçament de les falles, i en alguns casos, la manca d’estudis paleosísmics detallats por comprometre la fiabilitat dels models de perillositat. Cal doncs, focalitzar la futura recerca en aquestes falles menys estudiades. L’enfocament integral que s’ha seguit aqui, des de la recopilació de dades paleosísmiques fins al PSHA, contribueix a realitzar interpretacions més crítiques de la perillositat sísmica i pretén servir d’exemple per d’altres regions de sismicitat baixa-moderada.

High seismicity coupled with high population density creates a recipe for high seismic risk in Taiwan. Taiwan is located at the convergences of the Eurasian and Philippine Sea plates. These convergences result in the development of an accretionary wedge. A basal decollemont bounds the NE-SW trending thrust packages. The most Eastern thrust package, the Central Range, experiences high erosion rates and exhumation rates which may induce high seismicity. Paleoseismic indicators improve the ancient seismic history and may aid in the constraint of geologic processes of an accretionary wedge. Pseudotachylytes, known as earthquake fossils, form by frictional melting during seismic slip. Cataclasites form by comminution during sliding. Frictional melts serve as a window to the fault plane. Pseudotachylytes may allow for the assessment of focal parameters through the utilization of fault plane geometry and slip surface properties. This study provides the first microstructural evidence for fault pseudotachylytes at the Hoping River locality in Eastern Taiwan. The 3.3 Ma Hoping River frictional melt evidences an ancient Mw 6.4 ±0.40 earthquake. This pseudotachylyte demonstrates an oblique fault with a reverse component which corresponds to the orientation of the thrust packages in the accretionary wedge. Sense of slip of both pseudotachylytes and cataclasites suggest a uniform stress field. Narrow fault cores suggest high strain localization. Coeval pseudotachylyte and quartz-calcite veins suggest shear heating as a mechanism, if a fluid reservoir along the basal decollemont in Taiwan exists.

Oblique continental collision between the Pacific and Australian Plates in the central South Island of New Zealand (between c. 44 and 46°S) results in distributed reverse faulting. Only a few of these faults have been studied in detail, highlighting a major knowledge deficit in the earthquake behaviour, magnitude potential and contribution to seismic hazard for many faults in this part of the orogen. Three reverse faults are investigated in detail in this thesis: the Moonlight Fault Zone (MFZ), the Fox Peak Fault and the Forest Creek Fault. Geochronologic approaches, including Schmidt hammer exposure-age dating, radiocarbon dating, and optically stimulated luminescence dating, are combined with paleoseismic trenching, fault surface trace mapping, analysis of GPS and LiDAR survey data, and numerical modelling to characterise the rupture behaviour of these faults. A new Schmidt hammer chronofunction based on over 7000 clast analyses is developed that relates rebound value (R-value) to age for river terraces. The rapid, inexpensive, non-destructive, and statistically valid nature of this technique makes it widely applicable for age dating here and globally. I use Schmidt hammer exposure-age dating along with other geochronologic and surveying methods to show that stranded post-last glacial lake shorelines of Lake Wakatipu are undeformed and at a uniform elevation across the MFZ. This indicates an absence of uplift across the MFZ since c. 13 ka and suggests that this fault may be inactive or subject to long periods of interseismic quiescence despite its location in the active orogen. This result also challenges the long-held hypothesis that lake shorelines throughout central NZ are tilted due to isostatic rebound. Three segments of the Fox Peak Fault are identified through field mapping and surveying. Slip rates at over 50 locations along the 36.5 km total length of the fault (c. 1.5 mm yr⁻¹ maximum) co-vary with the bounding range topography and exhibit large gradients near intersecting NW-striking faults. Four paleoseismic trenches were excavated to determine if these segment boundaries represent barriers to earthquake rupture propagation. Evidence of 3-4 earthquakes since c. 16 ka on the two end segments with overlapping age uncertainties indicates that the recurrence interval of the fault is 2000-3000 years. The most recent event (MRE) occurred at c. 2.5 ka. Large single event displacement to length ratios on these segments and a single event scarp on the central segment indicate that while the segment boundaries control on-fault slip gradients, they are not likely to impede through-going ruptures in an earthquake. This is a relatively recent development from the long-term tectonic geomorphology, which is suggestive of range growth on separate faults.

In this study, a paleoseismic trench with limited age constraints that was previously excavated in 1990 across the central Garlock Fault near Christmas Canyon, in Searles Valley, California, was reopened to take advantage of new advances in luminescence dating techniques to investigate potential temporal variability in earthquake recurrence on the Garlock fault and to analyze previously unexposed older earthquake evidence. The trench exposed interbedded alluvial sand and pebble-gravels, with well-sorted, rounded, lacustrine sand from the most recent highstand of pluvial Lake Searles present at the base of the trench. Preliminary findings suggest at least 10 surface rupturing earthquake events occurred during the 10 k.y. time period exposed in the trench. To provide age constraints on the paleo-surface-rupturing events from the new trench, 54 luminescence samples were collected and the single-grain luminescence dating technique post- - was employed. The ages indicated that 7 events have occurred in the past ~7.2 ka, with at least 3 additional events in the more poorly stratified deeper section of the trench. This suggests a recurrence interval of ~1000 years. Event pattern seen at this trench did not exactly replicate the same pattern at other paleoseismic sites along the Garlock Fault. The most recent event seen at this trench occured within the same time period as the most recent events seen at the other paleoseismic sites on the central Garlock Fault.

Thesis (M.S.)--University of Nevada, Reno, 2006.
"December, 2006." Includes bibliographical references (leaves 58-62). Online version available on the World Wide Web. Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2006]. 1 microfilm reel ; 35 mm.

The Alpine Fault is a major plate boundary structure, which accommodates up to 50-80% of the total plate boundary motion across the South Island of New Zealand. The fault has not ruptured historically although limited off-fault shaking records and on-fault dating suggest large to great (~ Mw 8) earthquakes (every ~100-480 years; most recently in 1717), making it potentially one of the largest onshore sources of seismic hazard in New Zealand. The central section of the Alpine Fault, which bounds the highest elevations in the Southern Alps, is one of the most poorly characterised sections along the fault. On-fault earthquake timing in addition to the amount of dextral slip during major earthquakes was unknown along a 200-km-long section of the central Alpine Fault, while the amount of co-seismic hanging wall uplift was poorly known, prior to the present work. In this thesis I address these knowledge gaps through a combination of light detection and ranging (lidar), field, and stratigraphic mapping along with sample dating to constrain earthquake timing, style of faulting, and hanging wall rock uplift rates. Using lidar data coupled with field mapping I delineated the main trace of the Alpine Fault at Gaunt Creek as a north-striking fault scarp that was excavated and logged; this is part of a 2-km-wide restraining bend dominated by low-angle thrust faulting and without the clear strike-slip displacements that are present nearby (<5 km distant along strike in both directions). Where exposed in this scarp, the fault-zone is characterized by a distinct 5-50 cm thick clay fault-gouge layer juxtaposing hanging wall bedrock (mylonites and cataclasites) over unconsolidated late-Holocene footwall colluvium. An unfaulted peat at the base of the scarp is buried by post-most recent event (MRE) alluvium and yields a radiocarbon age of A.D. 1710–1930, consistent with sparse on-fault data, validating earlier off-fault records that suggest a 1717 MRE with a moment magnitude of Mw 8.1 ± 0.1, based on the 380-km-long surface rupture. Lidar and field mapping also enabled the identification and measurement of short (<30 m), previously unrecognized dextral offsets along the central section of the Alpine Fault. Single-event displacements of 7.5 ± 1 m for the 1717 earthquake and cumulative displacements of 12.9 ± 2 m and 22 ± 2.7 m for earlier ruptures can be binned into 7.1 ± 2.1 m increments of repeated dextral (uniform) slip along the central Alpine Fault. A comparison of these offsets with the local paleoseismic record and known plate kinematics suggests that the central Alpine Fault earthquakes in the past 1.1 ka may have: (i) bimodal character, with major surface ruptures (!Mw 7.9) every 270 ± 70 years (e.g. the 1717 event) and with moderate to large earthquakes (!Mw 7) occurring between these ruptures (e.g. the 1600 event); or (ii) that some shaking data may record earthquakes on other faults. If (i) is true, the uniform slip model (USM) perhaps best represents central Alpine Fault earthquake recurrence, and argues against the applicability of the characteristic earthquake model (CEM) there. Alternatively, if (ii) is true, perhaps the fault is “characteristic” and some shaking records proximal to plate boundary faults do not necessarily reflect plate-boundary surface ruptures. Paleoseismic and slip data suggest that (i) is the most plausible interpretation, which has implications for the understanding of major plate-boundary faults worldwide. Field mapping, geological characterisation, geophysical mapping, and optically stimulated luminescence (OSL) dating of on-fault hanging wall sediments were used to better constrain the geometry and kinematics of Holocene deformation along the rangefront of the Southern Alps at the Alpine Fault near the Whataroa River. The fault here is dextral-reverse, although primarily strike-slip with clear fault traces cutting across older surfaces of varying elevations. Deformational bulges are observed along these traces that are likely thrust-bounded. A terrace of Whataroa River sediments was found on the hanging wall of the Alpine Fault approximately ~ 55-75 m (when considering uncertainties) above the floodplain of the Whataroa River. OSL ages for a hanging wall sediments of 10.9 ± 1.0 ka for the aforementioned terrace, 2.8 ± 0.3 ka for Whataroa River terrace deposits in a deformational bulge, and 11.1 ± 1.2 ka for a rangefront derived fan indicate Holocene aggradation along the rangefront and hanging wall uplift rates of 6.0 ± 1.1 mm/yr. The sub-horizontal, laterally continuous, and planar-bedded Whataroa-sourced terrace deposits suggest that the adjacent bounding faults are steeply-dipping faults without geometries in the shallow subsurface that would tend to cause sedimentary bed rotation and tilting. Using data from the approximately 100-m deep pilot DFDP boreholes together with lidar and field mapping, I present a review of the Quaternary geology, geomorphology, and structure of the fault at Gaunt Creek, and estimate new minimum Late-Pleistocene hanging wall rock uplift rates of 5.7 ± 1.0 mm/yr to 6.3 ± 1.1 mm/yr (without considering local erosion) that suggest that the Southern Alps are in a dynamic steady state here. GPS-derived “interseismic” vertical uplift rates are < 1 mm/yr at the Alpine Fault, so the majority of rock uplift at the rangefront happens during episodic major earthquakes, confirming with on-fault data that slip occurs coseismically. Notably the uplift rates from both Mint and Gaunt Creek are consistent between the two sites although the primary style of faulting at the surface is different between the two sites, suggesting consistent coseisimc uplift of the Southern Alps rangefront along the Alpine Fault in major earthquakes. This thesis collected new on-fault datasets that confirm earlier inferences of plate-boundary fault behaviour. This study of the high-uplift central section of the Alpine Fault provides the first on-fault evidence for the MRE (i.e. 1717) and repeated of dextral slip during the MRE and previous events as well as new hanging wall uplift data which suggests that the majority of rangefront uplift occurs in earthquakes along the Alpine Fault. Because the fault has not ruptured for ~300 years, it poses a significant seismic hazard to southern New Zealand.

Faults have a controlling influence on a variety of geologic processes includingfluid flow, the mechanical behavior of the crust, and seismicity. The geologic sciences have long recognized that faults generate earthquakes; however, few indicators of ancient earthquakes exist in fault-zones. This dissertation documents several indicators for the preservation of ancient earthquakes in fault-zones including frictional melt (pseudotachylyte), highly-polished fault slip surfaces, and hydrothermal alteration. These deformation products result from rapid generation of frictional heat during earthquakes.This dissertation also focuses on the seismic potential of continental low-angle normal faults (LANF). We document the preservation of voluminous pseudotachylyte along a LANF suggesting that the fault repeatedly nucleated large earthquakes. Additionally, a synthesis of reported occurrences of LANF pseudotachylyte indicates that LANF seismicity is common during extension. This has important implication for the mechanics and evolution of LANFs and for the assessment of seismic hazards.We also present a little used, high resolution, and low-cost 3D range camera for use in geolgy. The KinectTM is a 3D infrared range camera that can be used to collect high- resolution (± 1 mm), 3D data in both field and laboratory settings. We describe the use of the KinectTM in geologic appications and recommend more widespread use.

Critical inputs to evaluate fault behavior models include the frequency of large earthquakes on plate boundary faults, amount of displacement, style of deformation in these events, and how these earthquakes are associated with adjacent sites and broader segments. Paleoseismic data provide these inputs and allow the characterization of hazard posed by individual faults. This dissertation presents results from paleoseismic studies at Hazel Dell and Frazier Mountain that provide new earthquake chronologies and slip estimates for the San Andreas Fault (SAF). These data provide new insights into the recurrence and style of coseismic deformation for surface rupturing earthquakes on the SAF. The Hazel Dell site provides the first definitive paleoseismic evidence of two pre-1906, 19th century earthquakes on the Santa Cruz Mountains section of the SAF. I correlate these paleoseismic findings with the historic record of ground shaking associated with earthquakes in that period and combine the style of deformation in the last 3 events at the site with results from nearby paleoseismic sites to estimate earthquake rupture lengths and magnitudes for these early historic events. These findings increase the frequency of historic surface rupturing earthquakes on the northern SAF three-fold. At the Frazier Mountain site, on the southern SAF, I mapped deformation across a releasing step on the fault for the last five surface rupturing earthquakes to estimate deformation per-event. I compare the geometry and amount of vertical relief generated across the step-over by retrodeforming 3D surfaces interpolated from paleoseismic data step-wise for stratigraphic units deformed by each of those earthquakes. I find that structural relief is similar in four of the last five events, so slip on the fault must be within the same range for these earthquakes to generate approximately equivalent structural relief across the step-over. These results suggest displacement on the fault is comparable at the Frazier Mountain site for the last 4 events, including deformation resulting from 4-5 m lateral displacements in the historic M 7.9 1857 earthquake. This dissertation includes previously published and unpublished coauthored material. Supplemental file Plate A includes additional trench logs for the Hazel Dell site, presented in Chapters II and III.

Geodetic observations of crustal deformation through the earthquake cycle provide unique opportunities to gain essential knowledge of faulting mechanisms, lithospheric rheology, and fault interaction. Normal faults, an integral geologic unit responsible for crustal deformation, are specifically investigated in this thesis, via three case studies in two significantly different tectonic environments: the 2008 Mw 6.3 Damxung and Mw 7.1 Yutian earthquakes on the Tibetan Plateau, and the 2005 Mw 7.8 Tarapaca earthquake in the northern Chile subduction zone. To move toward realistic slip models, I consider crustal layering for the Damxung earthquake, and non-planar rupture for the Yutian earthquake. The Damxung study shows that assuming a homogeneous crust underestimates the depth of slip and overestimates the magnitude, in comparison to a crustal model with a weak sedimentary lid. A curved fault model composed of triangular dislocation elements (TDEs) for the Yutian earthquake recovers the geodetic observation better than rectangular fault segments. Normal faulting earthquakes are characterized by shallow slip deficit, which is partially compensated by patchy afterslip around, but no deeper than, the coseismic rupture. The complementary and partially-overlapping relationship between coseismic slip and afterslip implies complexity of frictional properties in both down-dip and along-strike directions. Postseismic deformation induced by viscoelastic relaxation (VER) following normal faulting earthquakes is fundamentally different in pattern from that produced by afterslip. This difference enables identification of afterslip as the major postseismic mechanism for the Damxung and Yutian earthquakes, and VER for the Tarapaca earthquake. In addition to understanding the faulting mechanism, I also place constraints on local rheological structure. In central Tibet, where the Damxung earthquake occurred, lack of noticeable VER-related signal allows a lower bound of 1 × 1018 Pa s for the viscosity of the lower crust/upper mantle. In northern Chile, geodetic observations following the Tarapaca earthquake indicate a weak layer with viscosity of 4 – 8 × 10^18 Pa s beneath a higher-viscosity lower crust and mantle lithosphere, and a strong continental forearc. Based on the co- and post-seismic models, I investigate fault interaction from a perspective of static stress change. Stress computation suggests that the 2014 Mw 6.9 strike-slip event close to the Altyn Tagh fault occurred on a fault that was positively stressed by the Yutian earthquake, and the Altyn Tagh fault to the east of the 2014 rupture is a potential locus for future failure. Although the Coulomb stress change on the 2014 Iquique earthquake rupture is negative due to the Tarapaca earthquake and its postseismic VER process, positive loading on the shallow-dipping nodal plane of its M 6.7 preshock suggests that the Tarapaca earthquake may have acted as an indirect trigger of the 2014 Iquique earthquake. Both studies reveal the role played by normal faults in interacting with other types of faults and have implications for seismic hazard assessment.

Thesis (Ph. D.)--University of California, Riverside, 2009.
Includes abstract. Available via ProQuest Digital Dissertations. Title from first page of PDF file (viewed March 20, 2010). Includes bibliographical references. Also issued in print.

The analysis of marsh cores from the tidal zones of the Siuslaw, Umpqua, and Coos River systems on the south-central Oregon coast provides supporting evidence of coseismic subsidence resulting from megathrust earthquakes and reveals the landward extent of the zero-isobase. The analysis is based on lithostratigraphy, paleotidal indicators, microfossil paleotidal indicators, and radiocarbon age. Coseismic activity is further supported by the presence of anomalous thin sand layers present in certain cores. The analysis of diatom assemblages provides evidence of relative sea-level displacement on the order of 1 to 2 m. The historic quiescence of local synclinal structures in the Coos Bay area together with the evidence of prehistoric episodic burial of wetland sequences suggests that the activity of these structures is linked to megathrust releases. The distribution of cores containing non-episodically buried marshes and cores that show episodically buried wetlands within this area suggests that the landward extent of the zero-isobase is between 100 km and 120 km from the trench. The zero-isobase has a minimum width of 10 to 15 km. Radiocarbon dating of selected buried peat sequences yields an estimated recurrence interval on the order of 400 years. The apparent overlapping of the landward margin of both the upperplate deformation zone (fold and/or thrust fault belt) and the landward extent of the zero-isobase is interpreted to represent the landward limit of the locked zone. The earthquake magnitude is estimated to be 8.5 based on an arbitrary rupture length of 200 km and a locked zone width of 105 km. The identification of the zero-isobase on the southcentral Oregon coast is crucial to the prediction of regional coseismic subsidence and tsunami hazards, the testing of megathrust dislocation models, and the estimation of megathrust rupture areas and corresponding earthquake magnitudes in the Cascadia Margin.

An analysis of Earth deformation, earthquakes and tides has been undertaken using Earth tide and interferometric SAR data from ESA satellites. The ability of Earth tides to trigger earthquakes has been investigated by measuring the statistical relationship between earthquake occurrence and Earth tides. Analysing Earth tides data with earthquakes occurrence using Shuster’s test has shown that there is a correlation between Earth tides and earthquake occurrence. The significance of this correlation has been examined as a function of location, earthquake depth and magnitude. It has been found that the correlation is especially significant for low magnitude earthquakes. The two regions in California examined show similar correlations but significant differences in the phase angle of the correlation. Possible reasons for these differences and the role of ocean load tides are discussed in this thesis. SAR data are used to detect the Earth displacement related to two recent earthquakes in the Californian area. InSAR technique has been applied successfully to the Bam earthquake in Iran in 2003. The results for Earth displacements in the Parkfield area are less satisfactory but a number of interference fringes over a wide area due to a particular earthquake have been observed.

The Makran subduction zone (offshore Pakistan and Iran) has the largest accretionary prism of any margin worldwide, formed due to the thick incoming sediment section of up to 7.5 km. This margin has been relatively understudied, and this thesis presents a new, detailed structural and hydrological interpretation and seismogenic hazard assessment for the Makran. The accretionary prism is dominated by simple, imbricate thrusts which form seaward verging, anticlinal ridges up to 200 km long. The prism has a low average taper angle of 4.5°. Two oceanic basement features intersect the deformation front: The Little Murray Ridge (LMR), a discontinuous, largely buried seamount chain, and the Murray Ridge, a large transtensional ridge. The subduction of the LMR causes an increase in fault spacing, a seaward step in the position of the deformation front, and may segment earthquake rupture. The Murray Ridge influences the incoming sediment stratigraphy and reduces sediment thickness in the east. Fault activity in the Makran is widely distributed within the prism, with over 75% of faults showing some evidence for recent activity. This may be the result of the high levels of frontal accretion causing the Makran to behave as a sub-critical prism. The décollement in the outer prism occurs within the sediment section and is unreflective. There is extensive evidence for fluid and fluid migration in the Makran, with a widespread hydrate BSR, high amplitude gas zones in the shallow sediment, reflective fault sections (indicating high porosity and likely high pore pressure), and surface seeps. The spatial distribution of these features appears to be controlled by changes in the incoming section and fault activity, and significant fluids are trapped within anticlinal hinge zones. Reflective fault sections are concentrated in the upper sediments, and there is no evidence for a significant fluid contribution from the deeper (>4 km) sediment section. This may indicate that the lower sediment section is largely dehydrated, prior to accretion. The Makran experiences low seismicity compared to many global subduction zones, but produced a Mw8.1 tsunamigenic earthquake in 1945. Thermal modelling suggests that temperatures at the plate boundary are over 150°C at the deformation front due to the thick sediment section. These results suggest that the plate boundary may have the potential to be seismogenic to shallow depths. Thermal modelling also indicates that the shallow dip of the subducting plate produces a wide potential seismogenic zone, which when combined with along-strike rupture scenarios produces potential earthquake magnitudes of Mw8.7-9.2 with significant regional hazard implications.

The Centennial Mountains are an east-west trending mountain range in southwest Montana. The Centennial Mountains are bound on the south by the Eastern Snake River Plane, the north-trending Madison Range and fault on the east and the Centennial Valley on the north. The Centennial normal fault offsets the Centennial Mountains on the north down-dropping the Centennial Valley. Approximately 3000 meters of offset along the Centennial normal fault creates the Centennial Mountains. The present Centennial Mountains are subdivided into two stratigraphically different blocks by the Odell Creek normal fault. The eastern Centennial Mountains are interpreted as the upthrown block of the Odell Creek normal fault exposing Precambrian and Paleozoic rock along the northern face of the range. The western Centennial Mountains are interpreted as the downthrown block of the Odell Creek normal fault exposing Cretaceous and younger rocks. Both eastern and western segments of the Centennial Mountains are then offset along the range bounding Centennial normal fault. Offset along the Centennial normal fault started approximately 2.1 Ma as evidenced by the displacement of the 2.1 Ma Huckleberry Ridge tuff. It is believed that prior to the emplacement of the 2.1 Ma Huckleberry Ridge tuff, the Centennial Mountains had minimum to no surface relief. The majority of offset along the Centennial normal fault has occurred with in the late Pleistocene with estimated slip rates of 0.65-0.82 mm/yr. The late Pleistocene surface offsets along the Centennial Mountains have an average of 9.1-9.6 meters with similar offset seen along the eastern and western segments.

Earthquake ruptures along tectonically active faults nucleate predominantly at depths of 5 to 12km in the crust, so the portions of faults that slip in these events cannot be directly observed. The geometry and composition of seismogenic faults controls the nucleation, propagation and termination of the earthquake rupture process. This study aims to place constraints on the geometry and composition of seismogenic faults by examining ancient faults exhumed from the depths at which earthquakes are observed to nucleate. Faults exposed in the Sierra Nevada, California, show that the internal architecture of earthquake faults is heterogeneous at a variety of scales. Field and microstructural observations are used to describe in detail the architecture of two pseudotachylyte-bearing fault systems in the Granite Pass region of Sequoia and Kings Canyon National Park; the Granite Pass fault (GPF) and associated faults, and the Glacier Lakes fault (GLF) and faults that splay from the GLF. The GPF and sub-parallel faults are 1 to 6.7km long with left-lateral strike-slip displacements up to 80m. The GPF and GPF-parallel faults have architectures that are heterogeneous along strike. They are composed of one to four fault core strands containing cataclasites and ultracataclasites that cross-cut early localized crystal-plastic deformation. Slip surfaces developed at the edges of, within and between fault cores are defined by pseudotachylytes and cataclasites with thicknesses of ~0.01 to 20mm. Fault-related subsidiary structures are developed on either side of fault cores, and comprise damage zones with widths orthogonal to the fault of up to 30m. The GLF and splay faults have architectures that are more homogeneous along strike. These faults are composed of a tabular volume of heavily fractured and altered host rock between approximately planar fault core strands. The fault cores are centimetres wide and contain cataclasites and foliated cataclasites that are cross-cut by pseudotachylytes. Fault-related damage is limited in extent to several metres beyond the bounding fault cores. The GLF contains additional cataclasites, ultracataclasites and pseudotachylytes in a fault core strand within the tabular zone of fractured rock. Thermochronologic analyses of the host rock granodiorite, combined with previously published palaeogeobarometry and apatite fission track data, define the temperature and pressure changes associated with cooling and exhumation of the pluton. The P-T conditions prevalent during the deformation history of the GPF fault system are evaluated by relating recrystallisation mechanisms in quartz to temperature, showing that the early stages of deformation occurred at temperatures of 450 to 600ºC. Dating of pseudotachylytes by the K-Ar isotopic method suggests subsequent brittle deformation took place at temperatures <350ºC and pressures ≤150MPa. A model for the architecture of the GPF architecture therefore has well constrained environmental controls, and should be transferrable to faults with comparable deformation histories. Small faults (cumulative displacements <1m) in the Mount Abbot Quadrangle, 55km north of Granite Pass, have been examined to illustrate the processes associated with the earliest stages of slip in the Sierra Nevada faults. The faults have branched or straight fault traces. Pseudotachylytes in branching faults show that these faults accumulated displacement in high velocity slip events, rather than by quasi-static fault growth. Branching faults without pseudotachylytes contain chlorite breccias interpreted to have formed in response to slip along faults with elevated pore fluid pressure. Straight faults also likely underwent slip events, but contain cataclased chlorite and epidote, suggesting low fluid pressures during slip. The small faults show that fluid-rock interactions are critical to fault geometry, and that lateral structural heterogeneity is established after small finite displacements. Field and thin section observations of exhumed seismogenic faults show that fault architecture and fault rock assemblage are critical to the earthquake rupture process. The heterogeneous composition of slip surfaces in the GPF faults imply that melt lubrication cannot account for all of the dynamic slip weakening as there are no continuous pseudotachylyte generation surfaces through the fault zones. Multiple slip weakening mechanisms must have been active during single rupture events. Slip weakening mechanisms also change at a given point on the fault in response to continued deformation. Splay faults at the GLF termination suggest that structural complexity observed at the terminations of fault surface traces can also be expected at depth. The off-fault damage at the termination of the GLF will change the bulk elastic properties of the host rock and must be accounted for in models of rupture propagation beyond fault terminations, or across geometrical discontinuities. Additionally, aftershock distributions and focal mechanisms may be controlled by the geometry of structures present at fault terminations.

Au cours de la dernière centaine d’années, la faille nord-anatolienne (FNA) a déjà généré 9 séismes de magnitude supérieure à 7 en Turquie. Dans cette thèse nous investiguons la faille de Ganos qui est le segment occidental de la FNA. Cette faille fût responsable du séisme de Mürefte du 9 août 1912 (M 7. 3). La faille de Ganos est visible en surface sur 45-km alors que le reste est en mers Egée à l’est et Marmara à l’ouest. Cette faille de Ganos forme la section occidentale d’une large zone en « step-over » qui correspond au bassin losangique (pull-apart) de Marmara où le séisme de Kocaeli de 1999 fût localisé dans sa partie est. Les deux extrémités des ruptures de 1912 et de 1999 définissent une lacune sismique dans la mer de Marmara. Des analyses géomorphologiques sur les 45-km à terre de la faille de Ganos ont permis de décrire des structures typiques des failles en décrochement (ex : pull-apparts, bombements, step-over, rides de compression et décalage de rivières). La section à terre de la faille de Ganos est d’azimut ~N68°E, segmentée en deux step-over extensifs au niveau de Gölcük and Kavak. La combinaison entre les analyses morphologiques à terre et en mer suggèrent un minimum de 04 sous-segments limités par des complexités géométriques qui est de l’est à l’ouest comme suit : Le bassin central de Marmara, le coude de Ganos, step-over de Gölcük, step-over de Kavak and la dépression Saros. La dépression de Saros et le basin central de Marmara sont les plus importantes complexités structurales le long de la faille de Ganos et peuvent as ir comme barrière à la propagation de la rupture. Le déplacement cumulé calculé sur 69 localités, de la reconstruction tectonique permettent d’avoir un aperçu sur les caractéristiques de déformation du segment de Ganos à long terme et à court terme. Les mesures des déplacements de chenaux, des crêtes et une partie d’ancienne routes nous conduisent à évaluer un décalage entre 8 et 575m. Par ailleurs, nous suggérons un décalage (offset) plus important de 200m à 9000m basé sur la reconstruction du système hydrologique actuel. Une classification des décalages de chenaux montre 8 classes distinctes d’offset de glissement cumulée. Nous avons aussi utilisé les courbes de fluctuations du niveau de la mer noire afin de contraindre les période de fortes précipitations qui peuvent générer des incisions de chenaux. 5 groupes de glissement cumulé (de 70 à 300m) montrent une bonne corrélation avec un rehaussement du niveau de la mer conséquent à 4 ka, 10. 2 ka, 12. 5 ka, 14. 5 ka et 17. 5 ka. Les estimations du taux de glissement conduisent à un taux de glissement constant de of 17. 9 mm/an pour les dernières 20. 000 années et un taux de glissement variable de 17. 7 mm/an, 17. 7 mm/an, 17. 9 mm/an et 18. 9 mm/an pour les dernières 10. 2 ka, 12. 5 ka, 14. 5 ka et 17. 5 ka, respectivement. La paléosismologie a montré sur 03 sites (Güzelköy, Yeniköy and Yörgüç) des évidences de 8 événements sismiques, 5 datés entre 1043 – 835 BC et 1500 – 830 BC à Güzelköy et Yeniköy respectivement. Une meilleure datation a été contrainte pour les trois derniers événements à Güzelköy qui sont vraisemblablement des séismes en (1) 1343 ou 1344 (2) 1659 ou 1766b and (3) 1912. Nous suggérons deux scénarios de récurrence de séismes pour les derniers séismes en relation avec la faille de Ganos. Le scénario (1) conduit à une moyenne de récurrence de 285 ± 36 ans et englobe les événements de 1912, 1659, 1354/1344, 824, 484 alors que le scénario (2) est aussi valable si une récurrence non périodique des séismes est acceptée. La combinaison entre les analyses géomorphologiques et des résultats des tranchées conduit à un taux de glissement de la faille nord anatolienne au niveau de la région de Ganos. A Güzelköy deux paleo-chenaux présentement un décalage de 16 m et 21 m et conduit à un taux de 22. 3 ± 0. 5 mm/an pour ce dernier ~700 années et 26. 9 mm/an pour les 781 dernières années respectivement. A Yeniköy des datations des couches les plus profondes montre de 46 ± 1 m de décalage de chenal et donnant ainsi un maximum de 17 mm/an de taux de glissement. Le 9 août 1912 la région de Mürefte a été secouée par un séisme (M = 7,3) a frappé le long de la faille de Ganos et a provoqué de graves dégâts (Io = X) entre Tekirdag et de Çanakkale. Un deuxième grand choc s'est produit le 13 Septembre 1912 (M = 6,8) avec une zone épicentrale à l'ouest du choc principal, causant des destruction Io = VII à l'ouest de dommages Gaziköy et le long de la péninsule de Gallipoli. Des rupture en surface ont été enregistrées le long de la totalité des 45-km de la section en surface. Nous avons déterminé un glissement maximum de 5,5 m qui a été précédemment suggéré à 3 m par Ambraseys & Finkel et al. (1987). Nous prolongeons les mesures de glissement de Altunel et al. (2004) à partir de 31 localités à 45 avec une meilleure répartition le long de la faille. La distribution d’offsets indique qu'une certaine partie de la rupture est au large, c'est à dire dans la baie de Saros et Mer de Marmara. 73 enregistrement de sismogrammes historiques ont été collectés pour les événements du 9 août, 10 août et le 13 Septembre 1912. Des paires comparables ont été numérisées à l'aide du logiciels TESEO. La modélisation et deconvolution de la forme d'ondes sismiques a permis la récupération d'une fonction temps source en utilisant les événements du 13 Septembre et du 9 Août et fourni une fonction temps source de 40 secondes pendant le tremblement de terre du 9 août. Considérant une propagation unilatérale de la rupture de 3 km/s, cette durée implique longueur de rupture de 120 km, cohérente avec la dimension du séisme (Mw 7. 4). Les polarités P des ondes à 5 stations et des N68°E d’azimut de faille nous permet de déduire un mécanisme au foyer pour l’événement du 9 aout. L'ampleur du choc Septembre 13 exige 30 ± 10 km de rupture de surface et des contraint la terminaison ouest pour les 120 ± 20km de longueur de la rupture du 9 Août. Prenant en compte les deux événements, une position de l'épicentre dans la baie de Saros pour le choc du 13 septembre de 150 ± 20 km de longueur totale de rupture et s'étendrait de Saros en propageant vers l’est et rejoignant ainsi le bassin de Marmara central, en accord avec la complexité géométriques importantes le long de cette section de la faille nord-anatolienne. Par conséquent, la terminaison est de la rupture du 09 aout 1912 et la terminaison ouest de la rupture de 1999 impliquent un minimum de 100-km de lacune sismique dans la mer de Marmara. Cette longueur de faille suggère un séisme de magnitude M>7 qui devra être pris en compte dans l’évaluation du risque sismique de la région d’Istanbul
The North Anatolian Fault generated 9 large earthquakes (M>7) in Turkey during the last 100 years. We investigate the Ganos fault, the westernmost segment of the North Anatolian Fault that was responsible for the 9 August 1912 Mürefte earthquake (M 7. 3). The Ganos fault is exposed onland for 45 km while the rest is covered up by the Aegean and Marmara seas to the west and east respectively. The Ganos fault forms the western section of a large step-over area that corresponds to the Marmara pull-apart and experienced the 1999 Kocaeli earthquake on its east. The two ends of the 1912 and 1999 earthquake ruptures define the seismic gap in the Sea of Marmara. Geomorphic analysis along the 45-km-long onland section of the Ganos fault allowed documenting typical structures of strike slip faulting; i. E. Step-overs, pull-aparts, bends, pressure ridges, sag-ponds, offset ridges, shutter ridges and stream displacement. The onland section of the Ganos fault is expressed as ~N68°E striking linear geometry, segmented by two extensional step-overs at Gölcük and Kavak. The combined analysis of offshore and onland fault morphology suggests a minimum of 4 sub-segments limited by geometrical complexities which are from east to west, the Central Marmara basin, Ganos bend, Gölcük step-over, Kavak step-over and Saros Trough. The Saros Trough and the Central Marmara basin are the largest structural complexities along the Ganos fault and may serve as barriers to earthquake rupture propagation. Cumulative displacements determined at 69 localities and tectonic reconstructions provide insights on the long-term and short-term deformation characteristic of the Ganos fault segment. Measurements of displaced streams, ridges and partly ancient roads yield right lateral offsets ranging from 8 to 575 m. Furthermore, we suggest larger offsets from 200 to 9000 m based on reconstructions of the present-day drainage system. A classification of the stream offsets shows 8 distinct classes of cumulative slip. We used sea level fluctuation curves of the Black Sea in order to constrain the timing of high precipitations periods which can trigger channel incisions. Consecutive 5 cumulative slip groups (from 70 to 300 m) show well correlations with subsequent sea level rise periods at 4 ka, 10. 2 ka, 12. 5 ka, 14. 5 ka and 17. 5 ka. Slip rate estimations yield a constant slip rate of 17. 9 mm/yr for the last 20. 000 years and a variable slip rate of 17. 7 mm/yr, 17. 7 mm/yr, 17. 9 mm/yr and 18. 9 mm/yr for the last 10. 2 ka, 12. 5 ka, 14. 5 ka and 17. 5 ka, respectively. Paleoseismology at three sites (Güzelköy, Yeniköy and Yörgüç) showed evidence of 8 faulting events, 5 of which post-date 1043 – 835 BC and 1500 – 830 BC at Güzelköy site and Yeniköy site, respectively. A better timing was constrained for the last three events at Güzelköy which are most probably the earthquakes in (1) 1344 or 1354 (2) 1659 or 1766b and (3) 1912. We suggest two earthquake recurrence scenarios for the last historical earthquakes attributed to the Ganos fault. Scenario 1 yields an average recurrence interval of 285 ± 36 years and encompasses the 1912, 1659, 1354/1344, 824, 484 events, whereas Scenario 2 gives an average recurrence interval of 285 ± 93 years and includes the 1912, 1766, 1354/1344, 824, 484 events. Considering that earthquakes occur periodic the suitable seismic history corresponds to Scenario 1. However scenario 2 is also valid if a non-periodic earthquake occurrence is accepted. The combination of geomorphic analysis and trenching results provides slip rates for the North Anatolian Fault at the Ganos region. At Güzelköy two paleo-channels offset for 16 m and 21 m yield 22. 3 ± 0. 5 mm/yr for the last ~700 years and 26. 9 mm/yr for the last 781 years, respectively. At Yeniköy dating from the lowermost units of the 46 ± 1 m offset stream provided a maximum 17 mm/yr slip rate for the last 2840 years. The 9 August 1912 Mürefte earthquake (Ms=7. 3) struck along the Ganos fault causing severe destruction (Io = X) between Tekirdağ and Çanakkale. A second large shock occurred on 13 September 1912 (Ms = 6. 8) with an epicentral region to the west of the first main shock, giving rise to Io = VII damage west of Gaziköy and along the Gallipoli peninsula. Surface breaks have been recorded along the entire 45-km-long onland section. We determined a maximum slip of 5. 5 m that was previously suggested as 3 m (Ambraseys & Finkel et al, 1987). We extend the slip measurements of Altunel et al. , (2004) from 31 localities to 45 with a better distribution along the fault. The offset distribution indicates that a certain length of the rupture is offshore, i. E. , in the Saros bay and Sea of Marmara. 73 historical seismogram recordings have been collected for the 9 August, 10 August and 13 September 1912 shocks. Comparable pairs have been digitized using TESEO software. The modelling and deconvolution of seismic waveforms allowed retrieving a relative source time function using the 13 September and 9 August shocks and provided a source duration of 40 seconds for the 9 August earthquake. Considering a unilateral rupture propagation of 3 km/s, this duration implies rupture length of 120 km, consistent with the earthquake size (Mw 7. 4). P-wave polarities at 5 stations and field based N68°E fault strike allow us to construct the focal mechanism solution for the 9 August shock. The size of the 13 September shock requires 30 ± 10 km of surface faulting and constrains the western limit for the 120 ± 20 km long 9 August rupture. Taking into account the two events, an epicentre location in the Saros bay for the 13 September shock, the 150 ± 20 km long total rupture length would extend from Saros Trough towards east and reach the Central Marmara Basin, consistent with major geometric complexities along this section of the North Anatolian Fault. Therefore, the eastern termination of the 9 August 1912 rupture and the western termination of the 1999 earthquake rupture imply a minimum 100-km-long seismic gap in the Sea of Marmara. This fault length suggests an earthquake size M>7 that should be taken into account in any seismic hazard assessment for the Istanbul region

Thesis (M.S.)--University of Missouri-Columbia, 2008.
The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Title from title screen of research.pdf file (viewed on July 8, 2009) Includes bibliographical references.

Geodetic observations are commonly used to make inferences about the rheology of the lower crust and mantle, frictional properties of faults, and the structure of the Earth following an earthquake. On 24 September 2013, an Mw 7.7 earthquake ruptured a 200 km segment of the Hoshab fault in southern Pakistan. The Hoshab fault is located in the Makran accretionary prism, one of the widest emergent accretionary prisms on Earth. Interferometric synthetic aperture radar (InSAR) time series observations beginning 15 months after the 2013 earthquake capture a large displacement transient in the hanging wall of the Hoshab fault. Using simulations of viscoelastic relaxation and inversions for afterslip along five candidate fault geometries, I find that afterslip alone cannot account for the displacement observed in time series. Instead, I find that the observations can be explained by viscoelastic relaxation of a mechanically weak (viscosity on the order of 1017-1018 Pa s), shallow (>6 km) weak layer within the accretionary prism. First order results indicate this weak layer is between 8-12 km thick with a power law (n=3.5) rheology, and that viscoelastic relaxation is accommodated by dislocation creep at low temperatures. The weak nature of the Makran accretionary wedge may be driven by high pore fluid pressure from hydrocarbon development and underplated sediments.

This dissertation investigates natural deformation processes over multiple earthquake cycles in the seismically active, southern Junggar basin, NW China and additionally explores the capabilities of 3D geomechanical restoration as an effective tool for fractured reservoir characterization. Chapter 1 presents a detailed 3D fault model of the active Southern Junggar Thrust (SJT) – constrained by seismic reflection data – in the southern Junggar basin. This work demonstrates the significance of mid-crustal detachments as a physical mechanism to accommodate destructive, multi-segment earthquakes in active thrust sheets. Moreover, it highlights the efficacy of surface folds to delineate fault geometries at depth in the absence of subsurface data constraints. Chapter 2 describes active thrust sheet deformation across the Tugulu anticline, which sits in the hanging wall of the SJT, from Late Quaternary to present. Holocene terrace deformation records of surface faulting and folding yield consistent fault slip rates. We develop a quantitative method for extracting fault slip rates from terrace fold geometries using a mechanical modeling approach, yielding a 250 kyr history of SJT slip. This study provides new insights into natural fold growth associated with fault slip. Moreover, it addresses several shortcomings of traditional seismic hazards assessment methodologies. Chapter 3 characterizes the styles, timing, and sequence of deformation across southern Junggar. Southern Junggar underwent extension followed by tectonic inversion and shortening, forming a series of imbricate structural wedges. A kinematic model for the evolution of shear fault-bend fold wedges is presented. We discuss the implications of structural style, fold growth and thrusting sequence on the ~175 Myr evolution of this fold-and-thrust belt and its petroleum system. Chapter 4 investigates the impact of natural fold strains on fractured reservoir properties in the Permian Basin, West Texas. This study details the ability of 3D geomechanical restorations to accurately model natural strain distributions associated with fold growth. Modeled strains from geomechanical restorations are integrated with proxies for natural deformation and production data to describe how tectonic strain impacted observed gas production, water cuts and reservoir temperatures. When used in conjunction with additional datasets, geomechanical restoration shows promise for predictive abilities in characterizing conventional and unconventional fractured reservoir properties.
Earth and Planetary Sciences

This study area provides a unique opportunity to study the intersection of the Elsinore and West Salton detachment faults in southern California, effusing warm springs, and alteration products in the midst of the fault intersection. Structural mapping and compiling previous maps supply an interpretation of the fault zone geometries within the Tierra Blanca Mountains. Geochemical analysis of the crystalline basement and altered protolith help determine the effects of faulting and fluid flow in the study area. In the Tierra Blanca Mountains, the Elsinore strike-slip fault system transitions from the double-stranded Julian segment and Earthquake Valley fault in the northwest, to the single-stranded Coyote Mountain segment in the southeast. A network of cross faults striking northeast connects the fault segments. The Coyote Mountain segment encounters the inactive West Salton detachment fault in the study area. The detachment fault is a barrier to fluid flow and exhibits primarily brittle deformation, while the Coyote Mountain segment is a conduit for fluid flow along the northeastern flank of the Tierra Blanca Mountains. The damage zone of the Coyote Mountain segment reaches widths up to 500 m and contains intense fracturing and subsidiary faults striking parallel to the main trace. The tonalite protolith is bleached, stained, and altered from water-rock interactions. The most intense bleaching is at a county park, where the protolith is altered to clays and zeolites while the mineralogy of the stained regions contains iron oxides and clinochlore in addition to quartz, Ca-rich albite, and biotite preserved from the protolith. The water chemistry at Agua Caliente hot springs shows the fluid is partially equilibrated. Groundwater temperatures likely reached 75-85°C at depths up to 2.14 km before rising to the surface. Frequent seismicity in the study region is related to the spring characteristics including water level, conductivity, and temperatures. Spring temperature and conductivity displayed three behaviors during the summer 2011 logging period, attributed to seasonal changes and most likely local seismicity as well. Conductivity seems to be the property most influenced by earthquake activity in the area. Changes in fluid chemistry between sampling periods may indicate mixture with other fluid sources.

The Hines Creek fault (HCF) is a Holocene-active fault in central Alaska. Its trace has been mapped several times, but data on the history of fault displacement is scarce. As a major crustal-scale geologic boundary with uncertain Quaternary tectonic activity, it is a priority for more to be known about the activity of this fault to better understand the hazards it presents to the Denali National Park and Preserve and Alaskan infrastructure. This study characterizes the late Quaternary activity of the HCF through surficial geologic mapping and paleoseismic investigations. Mapping revealed a very steep (~84°-88° apparent dip), north dipping fault plane and measurements from offset Pleistocene outwash terraces revealed south side-down vertical offsets of up to 12 m, indicating a steeply dipping reverse fault. Three paleoseismic trenches excavated across the fault trace provided a record of seismic activity and hold evidence for at least four prehistoric earthquakes in the last 2 ka. Slip rate calculations estimate movement on the HCF to be between 0.6mm yr-1 and1.2 mm yr-1. The active trace of the HCF follows the southern margin of the tectonically active Mount Healy anticline, suggesting a kinematic linkage between the fault that underlies this anticline and the HCF.

In this thesis I combine data from 29 volcanic earthquake swarms that follow the pattern predicted by the Generic Volcanic Earthquake Swarm Model (GVESM; Benoit and McNutt, 1996) to investigate whether the relative timing of various parameters of pre-eruptive volcanic earthquake swarms could be used to forecast the time of an impending eruption. Based on the analysis of seismic unrest preceding many eruptions, the GVESM suggests that it is common to see an increase first in high-frequency earthquakes, then low-frequency earthquakes, then the onset of volcanic tremor. While this pattern is useful to volcano-seismologists, the relative timing and durations of these three different types of volcanic seismicity, is explored here for the first time. The parameters investigated are the onset times of (i) low-frequency (LF) events and of (ii) tremor, and the time at which (iii) the peak rate (PR) of volcano-tectonic (VT) events and (iv) the maximum magnitude (MM) earthquake occur in relation to normalized time defined by swarm onset and end (i.e., eruption). The normalized time starts at the swarm onset (0%) and ends with the eruption (100%) allowing a comparison and joint consideration of parameter occurrences across swarms of different actual duration. We identify the normalized onset time of for each parameter (LF, tremor, PR, MM) with respect to the duration of each swarm. Each swarm has onset time uncertainties of the swarm itself and of its parameters. A swarm with large onset uncertainty could bias the normalized onset time of each parameter and we use weighted means to decrease the influence of swarms with large uncertainties on overall results. The weighted means of LF onset, tremor onset, MM and PR occurrence are 79% ± 23%, 96% ± 10%, 78% ± 29% and 75% ± 34%, respectively. Errors are the standard deviation of each parameter. The uncertainties for LF, MM and PR are large because their normalized onset times have the characteristics of a uniform distribution and therefore seem to have no predictive value. In contrast, tremor onset has a narrow distribution towards the end of swarms. A possible tremor mechanism consistent with this observation could be boiling of groundwater as magma nears the surface. LF onset always seems to precede tremor onset. LF and tremor start early (at less than 80% of normalized time) at five volcanoes with high SiO2 content possibly related to lower density and higher gas content of the resulting magma.

Thesis (Ph. D.)--Washington State University, December 2008.
Title from PDF title page (viewed on Oct. 22, 2009). "Department of Civil & Environmental Engineering." Includes bibliographical references (p. 166-171).

The Mw 7.1 Darfield earthquake generated a ~30 km long surface rupture on the Greendale Fault and significant surface deformation related to related blind faults on a previously unrecognized fault system beneath the Canterbury Plains. This earthquake provided the opportunity for research into the patterns and mechanisms of co-seismic and post-seismic crustal deformation. In this thesis I use multiple across-fault EDM surveys, logic trees, surface investigations and deformation feature mapping, seismic reflection surveying, and survey mark (cadastral) re-occupation using GPS to quantify surface displacements at a variety of temporal and spatial scales. My field mapping investigations identified shaking and crustal displacement-induced surface deformation features south and southwest of Christchurch and in the vicinity of the projected surface traces of the Hororata Blind and Charing Cross Faults. The data are consistent with the high peak ground accelerations and broad surface warping due to underlying reverse faulting on the Hororata Blind Fault and Charing Cross Fault. I measured varying amounts of post-seismic displacement at four of five locations that crossed the Greendale Fault. None of the data showed evidence for localized dextral creep on the Greendale Fault surface trace, consistent with other studies showing only minimal regional post-seismic deformation. Instead, the post-seismic deformation field suggests an apparent westward translation of northern parts of the across-fault surveys relative to the southern parts of the surveys that I attribute to post-mainshock creep on blind thrusts and/or other unidentified structures. The seismic surveys identified a deformation zone in the gravels that we attribute to the Hororata Blind Fault but the Charing Cross fault was not able to be identified on the survey. Cadastral re-surveys indicate a deformation field consistent with previously published geodetic data. We use this deformation with regional strain rates to estimate earthquake recurrence intervals of ~7000 to > 14,000 yrs on the Hororata Blind and Charing Cross Faults.

Thesis (Ph. D.)--Joint Program in Oceanography/Applied Ocean Science and Engineering (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2012.
Cataloged from PDF version of thesis.
Includes bibliographical references.
Oceanic transform faults that accommodate strain at mid-ocean ridge offsets represent a unique environment for studying fault mechanics. Here, I use seismic observations and models to explore how fault structure affects mechanisms of slip at oceanic transforms. Using teleseismic data, I find that seismic swarms on East Pacific Rise (EPR) transforms exhibit characteristics consistent with the rupture propagation velocity of shallow aseismic creep transients. I also develop new thermal models for the ridge-transform fault environment to estimate the spatial distribution of earthquakes at transforms. Assuming a temperature-dependent rheology, thermal models indicated that a significant amount of slip within the predicted temperature-dependent seismogenic area occurs without producing large-magnitude earthquakes. Using a set of local seismic observations, I consider how along-fault variation in the mechanical behavior may be linked to material properties and fault structure. I use wide-angle refraction data from the Gofar and Quebrada faults on the equatorial EPR to determine the seismic velocity structure, and image wide low-velocity zones at both faults. Evidence for fractured fault zone rocks throughout the crust suggests that unique friction characteristics may influence earthquake behavior. Together, earthquake observations and fault structure provide new information about the controls on fault slip at oceanic transform faults.
by Emily Carlson Roland.
Ph.D.

In 1852, a five-minute long earthquake hit the Banda Arc region that was felt over most of Indonesia. It caused uplift of new islands and sent a tsunami across the Banda Sea that reached a height of 8 meters at Banda Neira and was also registered at Ambon, Saparua and other islands. Records of the 1852 earthquake at multiple locations provide the constraints needed to reconstruct the disastrous event through earthquake intensity analysis and numerical modeling of the tsunami. Using tsunami heights and arrival times as the major constraints, best fit numerical models of the tsunami were constructed using Clawpack. These models indicate that the earthquake was most likely a mega-thrust event along the Tanimbar Trough with a Mw of around 8.4. At least 10-15 meters of elastic strain energy has accumulated along the Tanimbar Through since the 1852 event, and the population in the region has increased exponentially. When another event occurs ≥ that in 1852, there will be many more people and treasure in harms way.

The seismogenic zone of subduction margins has the potential to generate some of the world’s largest earthquakes. A detailed study of the 2010 Mw 8.8 Maule, Chile rupture has enabled interpretation of the controls that govern subduction zone seismic behaviour across the earthquake cycle. In this thesis, we focus on two aspects of the central Chile margin: (1) imaging physical properties in the forearc and along the plate interface; (2) assessing source complexity of megathrust ruptures. We exploit a dataset of seismic body wave onset times from local aftershocks recorded on a temporary network to derive a 3-D seismic velocity model of the Maule rupture area. We image the main domains of the subduction zone and find a high velocity anomaly located along the plate interface, which we initially interpret as a subducted topographic high. We then develop a second, more accurate velocity model that uses an improved arrival time dataset together with observations from ocean-bottom seismometers. This refined model gives a sharper view of both the plate interface close to the trench, and the marine forearc. We show that ancient blocks of dense mantle in the lower forearc may have decelerated slip during the Maule earthquake and contributed to its nucleation. Furthermore, we infer that fluid saturated sediments inhibited significant slip close to the trench. We study source processes of a large aftershock of the Maule sequence, the 2011 Mw 7.1 Araucania earthquake, by inverting local seismic waveforms for a multiple point-source faulting solution. We find this earthquake constituted rupture on the plate interface followed by almost instantaneous slip along a normal fault in the overriding plate: the first observation of its kind. The second rupture of this closely-spaced doublet was hidden from teleseismic faulting solutions, and may have been dynamically triggered by S-waves from the first event. Overall, our work highlights the role played by the upper plate in subduction zone seismogenesis. We suggest that seismic velocities can help to characterise the behaviour of future large megathrust earthquakes. We show that the potential hazard posed by closely-spaced doublets involving the upper plate should be accounted for in real-time tsunami warning systems by using local waveform analysis.

The goal of this study is to develop probabilistically based empirical correlations for seismic performance assessment of buried pipelines. Within the scope of these research efforts, pipeline performance case histories have been compiled from Duzce city after Duzce earthquake. The characteristics of Duzce water supply and distribution system with the earthquake damage on the system were studied. Correlations of the damage patterns with the water distribution system, earthquake and geotechnical characteristics have been developed. Moreover spatial distributions of the earthquake effects havebeen transferred into Geographic Information System (GIS) format. As a result of these studies, it was intended to define the seismic, geotechnical and structural parameters which may explain the spatial variability of the observed seismic pipeline hazard. For the development of such correlations, a maximum likelihood framework for the probabilistic assessment of seismically induced buried pipeline performance is described. A database, consisting of postearthquake field observations of buried pipeline performance after Duzce earthquake in conjunction with in-situ index test results, is used for the development of probabilistically based seismic pipeline performance correlations. As a result of careful processing of available data, the variables of the problem are selected as: liquefaction susceptibility of soil, thickness of soft soil layer if it exists, peak ground acceleration and estimated ground deformations. A limit state function is defined in terms of these variables. Repairs on the pipeline system due to earthquake are compiled with the surrounding soil and earthquake parameters and the correlations of pipeline performances with the mentioned variables are determined. Different sets of fragility curves are developed for seismic pipeline performance problem, representing various sources of uncertainty that are intrinsic to the problem. Such information is believed to be useful to utility system operators in planning a seismic retrofit or upgrade program for existing pipeline systems.

Temporally and spatially clustered earthquake sequences along plate boundary zones indicate that patterns of seismicity may be influenced by earthquake-induced stress changes. Many studies invoke Coulomb stress change (CSC) as one possible geo-mechanical mechanism to explain stress interactions between earthquakes, their aftershocks, or large subsequent earthquakes; however, few address the statistical robustness of CSC triggering beyond spatial correlations. To address this, I evaluate the accuracy of CSC predictions in subduction zones where Earth’s largest earthquakes occur and generate voluminous and diverse aftershock sequences. A series of synthetic tests are implemented to investigate the accuracy of inferred stress changes predicted by slip distributions inverted from suites of geodetic observations (InSAR, GPS, seafloor geodetic observations) that are increasingly available for subduction zone earthquakes. Through these tests, I determine that inferred stress changes are accurately predicted at distances greater than a critical distance from modeled slip that is most dependent on earthquake magnitude and the proximity of observations to the earthquake itself. This methodology is then applied to the 2010 Mw 8.8 Maule, Chile earthquake sequence to identify aftershocks that may be used to perform statistically robust tests of CSC triggering; however, only 13 aftershocks from a population of 475 events occurred where confidence in CSC predictions is deemed to be high. The inferred CSC for these events exhibit large uncertainties owing to nodal plane uncertainties assigned to the aftershock mechanisms. Additionally, tests of multiple published slip distributions result in inconsistent stress change predictions resolved for the 13 candidate aftershocks. While these results suggest that CSC imparted by subduction megathrust earthquakes largely cannot be resolved with slip distributions inverted from terrestrial geodetic observations alone, the synthetic tests suggest that dramatic improvements can be made through the inclusion of near-source geodetic observations from seafloor geodetic networks. Furthermore, CSC uncertainties will likely improve with detailed earthquake moment tensor catalogs generated from dense regional seismic networks.

Six earthquake acceleration time histories were used to evaluate the groundmotion response of two sites, VSAP and VSAS, near the New Madrid Seismic Zone. These earthquakes ranged in magnitude from Mw 3.6 to Mw 5.2 and were located 46 to 173 km away from the recording instruments. These two sites are underlain by thick sequences (100 and 590 m) of unlithified soil that have been shown to greatly influence earthquake ground motions. Near-surface soil dynamic properties were characterized at the two sites using seismic SH-wave refraction, P-S suspension logging, borehole electrical logs, and geotechnical logging methods. The soil properties were developed into a soil model for each site and the soil models were used to compare theoretical ground-motion models to the actual strong-motion time histories. An 1-D ground-motion simulation program (EERA) was used to complete the theoretical ground-motion analysis. The results of the model indicated that the soils underlying VSAP generated amplification factors of 0.9 to 2.9 at about 6 and 9 Hz. Soils underlying VSAS generated amplification factors of 1.8 to 4.2 at about 5 Hz. These values correlated well with the observations at the two sites.

Chapter 1-2:The Cassini RADAR mapper has imaged elevated blocks and mountains on Titan we term ‘ridges’. Two unresolved problems regarding Titan's surface are still debated: what is the origin of its ridges and was there tectonic activity on Titan? To understand the processes that produced the ridges, in this study, (1) we analyze the distribution and orientation of ridges through systematic geomorphologic mapping and (2) we compare the location of the ridges to a new global topographic map to explore the correlation between elevation and ridges and the implications for Titan's surface evolution. Globally, the orientation of ridges is nearly E-W and the ridges are more common near the equator than at the poles, which suggests a tectonic origin for most of the ridges on Titan. In addition, the ridges are found to preferentially lie at higher-than-average elevations near the equator. We conclude the most reasonable formation scenario for Titan's ridges is that contractional tectonism built the ridges and thickened the icy lithosphere, causing regional uplift. The combination of global and regional tectonic events, likely contractional in nature, plus enhanced fluvial erosion and sedimentation near the poles, would have contributed to shaping Titan's tectonic landforms and surface morphology to what we see today. However, contractional structures (i.e. thrusts and folds) require large stresses (8~10 MPa), the sources of which probably do not exist on Titan. Liquid hydrocarbons in Titan's near subsurface must play a role similar to that of water on Earth and lead to fluid overpressures, which enable contractional deformation at smaller stresses (< 1MPa) by significantly reducing the shear strength of materials. We show that crustal conditions with enhanced pore fluid pressures on Titan favor the formation of thrust faults and related folds, in a contractional stress field. The production of folds, as on Earth, is facilitated by the presence of crustal liquids to weaken the crust. These hydrocarbon fluids have played a key role in Titan's tectonic evolutionary history, leaving it the only icy body on which strong evidence for contractional tectonism exists. Chapter 3: Arthur Wichmann's ‘Earthquakes of the Indian Archipelago’ documents several large earthquakes and tsunami throughout the Banda Arc region that can be interpreted as mega-thrust events. However, the source regions of these events are not known. One of the largest and well-documented events in the catalog is the great earthquake and tsunami affecting the Banda islands on 1 August 1629. It caused severe damage from a 15-meter tsunami that arrived at the Banda Islands about a half hour after violent shaking stopped. The earthquake was also recorded 230 km away in Ambon, but no tsunami is mentioned. This event was followed by at least 9 years of uncommonly frequent seismic activity in the region that tapered off with time, which can be interpreted as aftershocks. The combination of these observations indicates that the earthquake was most likely a mega-thrust event. We use an inverse modeling approach to numerically reconstruct the tsunami, which constrains the likely location and magnitude of the 1629 earthquake. Only linear numerical models are applied due to the low-resolution of bathymetry in the Banda Islands and Ambon. Therefore, we apply various wave amplification factors (1.5 to 4) derived from simulations of recent, well-constrained tsunami to bracket the upper and lower limits of earthquake moment magnitudes for the event. The closest major earthquake sources to the Banda Islands are the Tanimbar and Seram Troughs of the Banda subduction/collision zone. Other source regions are too far away for such a short arrival time of the tsunami after shaking. Moment magnitudes predicted by the models in order to produce a 15 m tsunami are Mw of 9.8 to 9.2 on the Tanimbar Trough and Mw 8.8 to 8.2 on the Seram Trough. The arrival times of these waves are 58 minutes for Tanimbar Trough and 30 minutes for Seram Trough. The model also predicts 5 meters run-up for Ambon from a Tanimbar Trough source, which is inconsistent with the historical records. Ambon is mostly shielded from a wave generated by a Seram Trough Source.We conclude that the most likely source of the 1629 mega-thrust earthquake is the Seram Trough. Only one earthquake > Mw 8.0 is recorded instrumentally from the eastern Indonesia region although high rates of strain (50-80 mm/a) are measured across the Seram section of the Banda subduction zone. Enough strain has already accumulated since the last major historical event to produce an earthquake of similar size to the 1629 event. Due to the rapid population growth in coastal areas in this region, it is imperative that the most vulnerable coastal areas prepare accordingly.

The late Miocene Cedar Springs fault system is a high-angle transpressional system in the Silverwood Lake area, western San Bernardino Mountains, southern California. This thesis presents the study of oblique-slip faults with modest amounts of slip, which represent the early stages of fault development by using slip as a proxy for maturity. A structural and geochemical characterization is provided for six fault zones ranging from 39 m of slip to 3.5 km of offset in order to develop a model of fault zone geometry and composition. Basic geometric and kinematic results are provided for an additional 29 small-displacement (cm- to m-scale) faults. The main faults of this study can be divided into the fault core composed of sheared clay gouge and micro breccia, the primary damage zone made up of chemically altered rock with microstructural damage and grain-size reduction, and the secondary damage zone, which is characterized by an increased fracture density relative to the host rock. Although there appears to be a general increase in fault core thickness with increasing slip, the correlation is insignificant when analyzing all faults. Both the primary and secondary damage zones appear to thicken with increased slip on the main fault. Overall, the structure and composition of the faults studied here are similar to those of larger strike-slip and reverse faults. This indicates that the fault core develops early in a fault's history. Subsequent slip appears to be focused along these narrow zones, with some deformation accumulating in the damage zone. Whole-rock geochemical analyses typically show a reduction in the abundance of Na, Al, K, and Ca in the fault core and primary damage zone relative to the host rock. This indicates enhanced fluid-rock interactions in these zones. Calculations of the energy consumed to produce the chemical alteration in the fault core indicate that a considerable amount of the total earthquake energy may be lost to alteration. This thesis concludes that fault processes are similar throughout the different stages of development, and the study of relatively small-displacement faults can therefore be used to understand fault evolution through time and the processes of larger faults in the brittle crust.

The structure and geomorphology of active orogens evolves on time scales ranging from a single earthquake to millions of years of tectonic deformation. Analysis of crustal deformation using new and established remote sensing techniques, and integration of these data with field mapping, geochronology and the sedimentary record, create new opportunities to understand orogenic evolution over these timescales. Timor Leste (East Timor) lies on the northern collisional boundary between continental crust from the Australian Plate and the Banda volcanic arc. GPS studies have indicated that the island of Timor is actively shortening. Field mapping and fault kinematic analysis of an emergent Pliocene marine sequence identifies gentle folding, overprinted by a predominance of NW-SE oriented dextral-normal faults and NE-SW oriented sinistral-normal faults that collectively bound large (5-20km2) bedrock massifs throughout the island. These fault systems intersect at non-Andersonian conjugate angles of approximately 120° and accommodate an estimated 20 km of orogen-parallel extension. Folding of Pliocene rocks in Timor may represent an early episode of contraction but the overall pattern of deformation is one of lateral crustal extrusion sub-parallel to the Banda Arc. Stratigraphic relationships suggest that extrusion began prior to 5.5 Ma, during and after initial uplift of the orogen. Sedimentological, geochemical and Nd isotope data indicate that the island of Timor was emergent and shedding terrigenous sediment into carbonate basins prior to 4.5 Ma. Synorogenic tectonic and sedimentary phases initiated almost synchronously across much of Timor Leste and <2 Myr before similar events in West Timor. An increase in plate coupling along this obliquely converging boundary, due to subduction of an outlying continental plateau at the Banda Trench, is proposed as a mechanism for uplift that accounts for orogen-parallel extension and early uplift of Timor Leste. Rapid bathymetric changes around Timor are likely to have played an important role in evolution of the Indonesian Seaway. The 2010 Mw 7.1 Darfield (Canterbury) earthquake in New Zealand was complex, involving multiple faults with strike-slip, reverse and normal displacements. Multi-temporal cadastral surveying and airborne light detection and ranging (LiDAR) surveys allowed surface deformation at the junction of three faults to be analyzed in this study in unprecedented detail. A nested, localized restraining stepover with contractional bulging was identified in an area with the overall fault structure of a releasing bend, highlighting the surface complexities that may develop in fault interaction zones during a single earthquake sequence. The earthquake also caused river avulsion and flooding in this area. Geomorphic investigations of these rivers prior to the earthquake identify plausible precursory patterns, including channel migration and narrowing. Comparison of the pre and post-earthquake geomorphology of the fault rupture also suggests that a subtle scarp or groove was present along much of the trace prior to the Darfield earthquake. Hydrogeology and well logs support a hypothesis of extended slip history and suggests that that the Selwyn River fan may be infilling a graben that has accumulated late Quaternary vertical slip of <30 m. Investigating fault behavior, geomorphic and sedimentary responses over a multitude of time-scales and at different study sites provides insights into fault interactions and orogenesis during single earthquakes and over millions of years of plate boundary deformation.

In the central United States, undefined earthquake sources, long earthquake recurrence intervals and uncertain ground motion attenuation models have contributed to an overstatement of regional seismic hazard for the New Madrid Seismic Zone on the National Seismic Hazard Maps. This study examined concerns regarding scientific uncertainties, overly stringent seismic mitigation policies and depressed local economy in western Kentucky through a series of informal interviews with local businessmen, public officials, and other professionals in occupations associated with seismic mitigation. Scientific and relative economic analyses were then performed using scenario earthquake models developed with FEMA’s Hazus-MH software. Effects of the 2008 Wenchuan earthquake in central China and seismic mitigation policies in use there were considered for potential parallels and learning opportunities. Finally, suggestions for continued scientific research, additional educational opportunities for laymen and engineering professionals, and changes in the application of current earthquake science to public policy in the central United States were outlined with the goal of easing western Kentucky economic issues while maintaining acceptable public safety conditions.

Rupture of the Chelungpu fault during the September 21, 1999, 7.6 Mwearthquake in Taiwan caused a 90-Jr,m-long surface rupture with variable displacement along strike. Analysis of core from two holes drilled through the fault zone, combined with geologic mapping and detailed investigation from three outcrops, define the fault geometry and physical properties of the Chelungpu fault in its northern and southern regions. In the northern region, the fault dips 45-60° east parallel to bedding and consists of a narrow (1-20 cm) core of dark-gray, sheared clay gouge at the base of a 30-50 m zone of increased fracture density that is confined asymmetrically to the hanging wall. Microstructural analysis of the fault gouge indicates the presence of extremely narrow clay zones (50-300 μm thick) that are interpreted as the fault rupture surfaces. Few shear indicators are observed outside of the fault gouge, which implies that slip was localized in the gouge in the northern region. Slip localization along a bed-parallel surface resulted in less high-frequency ground motion and larger displacements during the earthquake than in the southern region. Observations from the southern region indicate that the fault dips 20-30° at the surface and consists of a wide (20- 70 m-thick) zone of sheared, foliated shale with numerous gouge zones. A footwall-ramp geometry juxtaposes 2000-3000 m of flat-lying Quaternary Toukoshan Formation in the footwall with Pliocene and Miocene, east-dipping siltstone and muds tone in the hanging wall. The wide, diffuse fault zone contributed to the lower displacement and higher frequency ground motion in the southern region during the 1999 earthquake. The structure in the northern region is the result of the fault being a very young (<50 >ka) fault segment in the hanging wall of an older segment of the Chelungpu fault, buried in the Taichung basin. The fault in the southern region is located on an older (~1 Ma) fault trace. The contrasting fault properties in the different regions are responsible for the variability in strong-motion and displacement observed during the 1999 earthquake.