Дисертації з теми "Volcano seismology"
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Smith, Cassandra M. "Volcanic Electrification: A Multiparametric Case Study of Sakurajima Volcano, Japan." Scholar Commons, 2019. https://scholarcommons.usf.edu/etd/7950.
Повний текст джерелаSyahbana, Davy Kamil. "Seismological study of volcanic activity at Papandayan volcano, West Java, Indonesia." Doctoral thesis, Universite Libre de Bruxelles, 2013. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209395.
Повний текст джерелаLe monitoring sismique passif a débuté en décembre 2009 par l'installation d'une station sismique permanente à large bande dans le cratère du Papandayan. L'année suivante, une station météorologique a été installée pour compléter les mesures. La troisième année, 8 stations sismiques temporaires ont été déployées autour du volcan en réponse à une augmentation de l'activité sismique en 2011.
Nous avons conduit différentes études; (1) Nous avons examiné l'évolution de l'activité volcanique par réalisation d'une revue complète de l'histoire éruptive du volcan, autant pour la période préhistorique qu'historique. (2) Nous avons réalisé une analyse temps-fréquence des événements sismiques, étudié leurs caractéristiques et proposé une nouvelle classification avec une description des processus physiques supposés les générer. (3) Nous avons étudié les signatures sismiques précurseur de l'éruption de 2002 et pendant la crise volcanique de 2011 en implémentant différentes méthodologies, dont: la détection automatique d'événements sismiques à l'aide de filtres récursifs STA/LTA, l'analyse spectrale des formes d'onde, la mesure continue de l'amplitude spectrale du signal (SSAM), la polarisation des ondes et l'analyse de la distribution fréquence/magnitude (b-value). Nous avons alors réalisé un modèle chronologique des séquences sismiques du Papandayan. (4) Pour améliorer la compréhension de la dynamique des fluides sous le volcan Papandayan, nous avons réalisé une analyse des fréquences complexes des événements longue période (LP) et leurs variations temporelles peuvent être utilisées pour estimer (a) la composition des fluides présents dans les fractures sous le volcan et/ou (b) l'évolution des dimensions de ces fractures. Ces variations des fréquences complexes des événements LP peuvent être interprétées comme les réponses dynamiques du système hydrothermal à des changements d'impulsions de chaleur transférées par les flux de gaz volcaniques du magma sous le volcan. (5) nous avons calculé l'évolution temporelle du rapport spectral horizontal-sur-vertical (HVSR) en utilisant le bruit sismique ambiant enregistré par une station unique pour estimer les variations de vitesse de propagation des ondes de cisaillement en lien avec l'activité dynamique du volcan. Nous avons trouvé une corrélation claire entre les variations de fréquence de résonnance HVSR et l'augmentation de la sismicité.
Enfin, nous proposons des hypothèses sur les processus physiques qui se produisent sous le Papandayan. Cette étude est une première tentative d'utilisation de cette méthode pour surveiller l'activité volcanique en continu.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
Saballos, Jose Armando. "Short and Long Term Volcano Instability Studies at Concepción Volcano, Nicaragua." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4757.
Повний текст джерелаHeath, Ben. "New Constraints on the Magmatic System beneath Newberry Volcano from the Analysis of Active and Passive Source Seismic Data and Ambient Noise." Thesis, University of Oregon, 2015. http://hdl.handle.net/1794/18744.
Повний текст джерелаGeorge, Ophelia Ann. "The Geophysical Kitchen Sink Approach to Improving our Understanding of Volcano-Tectonic Interactions." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6504.
Повний текст джерелаBudi, Santoso Agus. "The seismic activity associated with the large 2010 eruption of Merapi volcano, Java : source location, velocity variation, and forecasting." Thesis, Grenoble, 2014. http://www.theses.fr/2014GRENU003/document.
Повний текст джерелаThe 2010 eruption of Merapi is the first large explosive eruption of the volcano that has been instrumentally observed. In this work, we study the eruption precursors and the pre-eruptive volcano behaviour by linking seismic features with other available observations. The main characteristics of the seismic activity during the 2010 crisis, including the chronology of seismicity, the spatio-temporal evolution of earthquake source positions and the seismic velocity changes, are presented. By performing absolute and relative locations, we obtain evidences of aseismic zones which are consistent with earlier studies and are interpreted as more ductile zones. Magma migration from the deep to the shallow part of the conduit through the upper aseismic zone is revealed by an upward shift of the hypocenters. We analyse the seismic energy quantified by RSAM calculated for several frequency bands. These functions display clear accelerations in the last few weeks before the eruption. This behaviour is used to perform hindsight eruption forecasting with the Material Failure Forecast method (FFM). The onset of the first eruption is estimated with a good precision. We propose an original method of event detection based on energy ratio. Using this method and waveform correlation, we identify 10 families of similar earthquakes. The seismic multiplets are located either below or above the upper aseismic zone and are composed of either volcano-tectonic or low-frequency events. Some of the clusters were active during several months before the eruptive crisis while a family that includes 119 repeating events appeared 20 hours before the eruption onset. Seismic velocity variations associated mainly with magmatic activity are estimated using the coda of both multiplets and noise cross correlation functions. These variations display strong temporal and spatial variability of their amplitude and sign. Although they cannot be described by a unique simple trend, these velocity variations can be considered as an eruption precursor. Using the preceding results together with other observations, we determine the specific features associated with the large explosive eruption of 2010. Furthermore, we propose a chronological scenario of the pre-eruptive activity of Merapi 2010 unrest
Smith, Cassandra Marie. "Ground-Coupled Air Waves: A Seismological Case Study of the Explosion Quakes of the 2007 Eruption of Pavlof Volcano, Alaska." Scholar Commons, 2015. https://scholarcommons.usf.edu/etd/5818.
Повний текст джерелаSpedalieri, Giancarlo. "Unravelling volcanic tremor source at mount etna from quantitative multiparametric analysis and moment tenso inversion." Doctoral thesis, Università di Catania, 2019. http://hdl.handle.net/10761/4134.
Повний текст джерелаRodgers, Melanie. "Unusual Patterns of Seismicity during Eruptive and Non-eruptive Periods at the Persistently Restless Telica Volcano, Nicaragua." Scholar Commons, 2013. http://scholarcommons.usf.edu/etd/4934.
Повний текст джерелаLanget, Nadège. "Détection et caractérisation massives de phénomènes sismologiques pour la surveillance d'événements traditionnels et la recherche systématique de phénomènes rares." Thesis, Strasbourg, 2014. http://www.theses.fr/2014STRAH017/document.
Повний текст джерелаFor some time now the quantity of available seismological data has kept increasing. Manually, their processing is long and tedious. Then, the automation of the detection, location and classification of seismic events has become necessary and aims to help the local observatories and to search and characterize some rarer or not well-known phenomena. The work is divided into 2 main directions : (1) the detection and location of seismic events with the Waveloc software (we improved the pre-existing tools, added some new functions for a more detailed analysis of the seimicity and applied the code to data from the Piton de la Fournaise volcano) ; (2) their classification (after computing the seismic attributes, we proved the efficiency and reliability of 2 supervised learning methods - logistic regression and SVM - for the Piton de la Fournaise volcano, underlined the difficulties for a more complex case - the Kawah Ijen volcano - and tried to apply new strategies)
Caudron, Corentin. "Multi-disciplinary continuous monitoring of Kawah Ijen volcano, East Java, Indonesia." Doctoral thesis, Universite Libre de Bruxelles, 2013. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209416.
Повний текст джерелаpart of Java island in Indonesia. Since 2010, the volcano has been equipped with seismometers
and several sensors (temperature and level) have been immersed in its acidic lake waters and in the acidic river seeping on the volcano flanks. While finding instruments capable of resisting to such extreme conditions (pH~0) has been challenging, the coupling of lake monitoring techniques with seismic data improves the knowledge of the volcanic-hydrothermal dynamics. Moreover, the monitoring capabilities have been considerably
enhanced supporting the decision-making of the authorities in case of emergency.
Several methods and processing techniques were used to analyze the seismic data. Much effort has been given to implement the seismic velocities (Moving Window Cross Spectral Analysis (MWCSA)) calculations. At Kawah Ijen, the frequency band that is less affected by the volcanic tremor and the seasonal fluctuations at the source ranges between 0.5-1.0 Hz. Moreover, a stack of 5 days for the current CCF gives reliable results with low errors and allows to detect fluctuations which are missed using a 10-day stack.
The background seismic activity mostly consists in low frequency events and a continuous tremor of low amplitude. Fluctuations of the lake temperature and level result from the recharge of the hydrothermal system during the rainy season. Kawah Ijen lake waters are not perfectly mixed and a shallow stratification occurs during the rainy season, because meteoric waters are less dense than the lake fluids.
Different unrest occurred during our study. Some of them strongly affected the volcanic lake, while others did only weakly. In the first category, a strong unrest commenced in October 2011 with heightened VT (Volcano Tectonic) earthquakes and low frequency events activity, which culminated mid-December 2011. This unrest was correlated with an enhanced heat and hydrothermal fluids discharge to the crater and significant variations of the relative velocities (~1%). This suggests an important build-up of stress into the system. VT earthquakes opened pathways for the fluids to ascend, by increasing the permeability of the system, which latter allowed the initiation of monochromatic tremor (MT) when the steam/gases interacted with the shallow portions of the aquifer. Our calculations evidence a higher contribution of steam in March 2012 that might explain the increase of the MT frequency when bubbles were observed at the lake surface. This period was also characterized by short-lived but strong velocity variations, related to water level
rises containing important amount of bubbles, and important heat and mass discharges
into the lake. On the contrary, the second category of unrest did only slightly affect the
lake system. This could be explained by a dryer hydrothermal system and/or locations of
the seismic sources, which were not directly linked to the lake.
While a magmatic eruption will likely be preceded by a strong seismic activity, the major challenges remain to understand why the unrest we studied did not lead to an eruption and to identify precursory signs of a phreatic eruption. Even a small phreatic eruption would be devastating for the people working everyday in the crater and the ones
who live nearby the voluminous acidic lake.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished
Lehto, Heather L. "Investigation of Stress Changes at Mount St. Helens, Washington, and Receiver Functions at the Katmai Volcanic Group, Alaska, with an Additional Section on the Assessment of Spreadsheet-based Modules." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4124.
Повний текст джерелаMilluzzo, Vincenzo. "Seismic chacterization of Vulcano island and Aeolian area by tectonic and seismo-volcanic events." Doctoral thesis, Università di Catania, 2013. http://hdl.handle.net/10761/1330.
Повний текст джерелаRoman, Diana Christine. "Changes in local stress field orientation in response to magmatic activity /." view abstract or download file of text, 2004. http://wwwlib.umi.com/cr/uoregon/fullcit?p3136443.
Повний текст джерелаTabod, Tabod Charles. "Seismological studies of the Cameroon Volcanic Line, in West Africa." Thesis, University of Leeds, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305583.
Повний текст джерелаSilva, de Victoria Pereira Jose Luis da. "Tectonic and volcanic seismicity following the 1995 eruption of Fogo, Cape Verde." Thesis, University of East Anglia, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.302150.
Повний текст джерелаChao, Kevin Tzu-Kai. "Global search of triggered non-volcanic tremor." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44779.
Повний текст джерелаTavarez, Samantha Catherine. "Geophysical Evidence for Mid-crustal Magma Reservoirs in the Lassen Volcanic Region, California." Scholar Commons, 2015. http://scholarcommons.usf.edu/etd/6038.
Повний текст джерелаRong, Tianyu. "Timing and Rates of Events in the Generic Volcanic Earthquake Swarm Model." Scholar Commons, 2019. https://scholarcommons.usf.edu/etd/7911.
Повний текст джерелаOhrnberger, Matthias. "Continuous automatic classification of seismic signals of volcanic origin at Mt. Merapi, Java, Indonesia." Phd thesis, [S.l. : s.n.], 2001. http://pub.ub.uni-potsdam.de/2001/0016/ohrnberg.pdf.
Повний текст джерелаLópez, Moreno Carmen. "Geophysical evidence of the preparedness for a volcanic eruption: El Hierro 2011-2012." Doctoral thesis, Universitat de Barcelona, 2017. http://hdl.handle.net/10803/461580.
Повний текст джерелаEl análisis de datos geofísicos y geodésicos en un amplia área que comprende al oeste la Dorsal Oceánica Atlántica, al norte la falla Azores-Gibraltar y el Sur de Iberia y al sur el NW de Marruecos y las Islas Canarias, nos ha permitido realizar un estudio entre la posible relación entre magmatismo y actividad tectónica. En concreto el estudiar su posible influencia en el desencadenamiento de la última erupción ocurrida en la isla de El Hierro en 2011. La ausencia de datos instrumentales previos que describen tal proceso en Canarias, nos dio la oportunidad de analizar por primera vez las señales geofísicas registradas antes, durante y después de un evento eruptivo, permitiendo el estudio de la actividad al emplazamiento y migración del magma a través de la litosfera. El objetivo de esta tesis doctoral es hacer una revisión integral de la física de este proceso eruptivo y sus causas, a través del análisis y procesamiento de datos geofísicos que se han registrado desde la época del primer registro instrumental existente en el área, el presente. Se consideran tres aspectos principales, centrados en el fenómeno eruptivo de El Hierro en diferentes escalas temporales y espaciales, pasando de lo general a lo específico. El primer aspecto es el estudio de la posible relación entre la geodinámica regional y el evento eruptivo de El Hierro 2011-2012. Se analizan los datos sísmicos y geodésicos adquiridos de 1996 a 2014, que abarcan desde el Atlántico Norte hasta el Oeste, hasta la frontera Azores-Gibraltar al Norte (incluido el margen NW-África) y Canarias. Un análisis conjunto permitió identificar signos tempranos de actividad tectónica anómala a partir de 2003, cuya intensidad aumentó en 2007, acelerándose tres meses antes del inicio de la erupción volcánica en El Hierro en octubre de 2011. El segundo aspecto es el estudio del periodo de unrest (10 Julio-10 Octubre). Los resultados muestran en El Hierro evidencias de: inyección de magma bajo la corteza, sobrepresurización, fracturación hidráulica (inicialmente de fluídos ricos en gas), migración hacia el Sur, superación del Moho desencadenando sismicidad inducida en fallas preexistentes y migración hacia la superficie, probablemente en condiciones de irreversibilidad. El tercer aspecto estudiado los las condiciones finales de ascenso de magma a la superficie y de establecimiento de la erupción (6 Octubre-15 Octubre), mostrando cambios en la geometría asociados al establecimiento del edificio volcánico, así como cambios en la composición del magma en los primeros días de la erupción.
Perrier, Laurence. "Apport de l'étude des sources sismo-volcaniques à la connaissance des processus éruptifs du volcan Yasur Vanuatu." Phd thesis, Université de Grenoble, 2011. http://tel.archives-ouvertes.fr/tel-00766993.
Повний текст джерелаHoopes, John C. "An Integrated Geophysical and Geologic Study of the Paleogene-Age Volcanic Body and Possible Landslide Deposit on the South Slope of the Traverse Mountains, Utah." BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2866.
Повний текст джерелаZigone, Dimitri. "Les trémors non volcaniques : observations et modélisations." Thesis, Grenoble, 2012. http://www.theses.fr/2012GRENU041/document.
Повний текст джерелаThe vision of the seismic cycle in subduction zones has considerably evolved over the last 10 years. New discoveries has pointed the diversity of slip behaviors in these zones with aseismic slow slip called « slow slip events » (SSE) and persistent low amplitudes vibrations called « non-volcanic tremors » (NVT). The goal of this thesis is to study the non-volcanic tremors in order to characterize these new manifestations of fault zones. We used two different approaches: 1. We first observed the non-volcanic tremors in the nature in order to characterize this phenomenon. The area of interest is the Guerrero seismic gap along the Mexican subduction zone. We develop a new detection and location method based on beamforming of correlations of seismic signals. This new method exhibits some characteristics of NVT: a complex source for a single tremor episode and a correlation between the NVT episodes and the long-term peak of movement velocity in southwards direction. Moreover, the study of the consequences of the Maule earthquake on the Mexican subduction zone showed that this earthquake triggered the 2009-2010 SSE in Guerrero. This triggering of slow slip is accompanied by strong seismic tremor actvity that are first modulated by the passing waves and then associated to the SSE. 2. We model numerically and experimentally the tremors in order to better understand their physical origin and their long-term evolution. We used a very slow friction experiment that indicates a systematic correlation between slip acceleration of a slider and emission of acoustic signals that are similar to NVT. A numerical modeling of the Mexican subduction zone is also presented and shows the possibility to reproduce NVT with a critical depinning transition
Tuladhar, Anisha. "Assessing Seasonal and Spatial Variability in the Hydrogeochemistry of Glacial Meltwater in Iceland." TopSCHOLAR®, 2017. http://digitalcommons.wku.edu/theses/1960.
Повний текст джерелаValade, Sébastien. "Dynamique des émissions pyroclastiques et mécanismes à la source : approche couplée par radar Doppler (VOLDORAD) et autres signaux géophysiques." Phd thesis, Université Blaise Pascal - Clermont-Ferrand II, 2012. http://tel.archives-ouvertes.fr/tel-00719570.
Повний текст джерелаTrovato, Claudio. "Séismes à longue période (LP) sur le Mt. Etna (Italie) : inversion du tenseur de moment et incertitudes liées à leur interprétation." Thesis, Orléans, 2015. http://www.theses.fr/2015ORLE2021/document.
Повний текст джерелаLong-period (LP) seismic events are abundantly recorded during rest and unrest periods at many volcanoes worldwide. However, their source mechanism is still poorly understood. Models which have been proposed so far to explain their origin are: 1) the resonance of a fluid-filled cavity triggered by fluid instabilities or the brittle failure of magma; 2) slow-rupture earthquakes occurring in the low consolidated materials composing the shallow portion of the volcanic edifice. Nowadays the main tool used to get insights into their nature is moment tensor (MT) inversion. MT inversions carried out in the past years focused mainly on the understanding of the physical origin of LP events and often supposed a relative simple geological structure of the medium. Recent studies highlighted the strong influence of shallow unconsolidated materials on the retrieved MT solutions and the importance of considering geological inhomogeneity in the inversion process. The principal aim of this thesis is to gain a better understanding of the source processes that generate LP events and to quantify the uncertainties related to the MT inversion process
Shuler, Ashley Elizabeth. "Investigations of Anomalous Earthquakes at Active Volcanoes." Thesis, 2012. https://doi.org/10.7916/D8ZG70BP.
Повний текст джерелаBraun, Thomas. "On the origin of seismic signals recorded on Stromboli volcano." Doctoral thesis, 2009. https://nbn-resolving.org/urn:nbn:de:bvb:20-opus-33376.
Повний текст джерелаThe main purpose of volcano-seismology concerns the qualitative and quantitative description of one or more unknown seismic source(s) located at some unknown depth beneath a volcano. Even if many different volcanoes show similar seismic signal characteristics, up to now it was not possible to find a standard seismic source model for volcanoes, as the double-couple in earthquake seismology. Volcanoes with a continuous activity, like Stromboli (Italy), represent for the volcano seismologist a perfect natural laboratory to address this question. This thesis treats the study of explosion-quakes and volcanic tremor recorded on Stromboli in a broadband frequency range, and discusses the location and the possible mechanisms of the seismic source(s). Seismic and infrasonic recordings of explosion-quake from Stromboli showed that the high-frequency phase propagates with a velocity of approximately 330 m/s. The seismic source can be explained as an explosion at the top of the magma column generated by rising gas bubbles. The seismic P-wave and the air-wave are both generated in the same point at the same time. The different path lengths and velocities for the seismic wave and the air-wave result in a difference in arrival times dt, that could be used to deduce the magma level and sound speed in the eruption column inside the conduit. Stations installed near the active crater reveal that infrasonic and seismic recordings of the short-period tremor (> 1 Hz) share the same spectral content and show similar energy fluctuations. Therefore, the short-period volcanic tremor at Stromboli originates from the continuous out-bursting of small gas bubbles in the upper part of the magmatic column. The spectrum of the long-period tremor recorded at Stromboli consists of three main peaks with periods at 4.8 s, 6 s and 10 s, and amplitudes varying with the regional meteorological situation. Hence, they are not generated by a close volcanic source but rather by ocean microseisms (OMS). The passage of a local cyclone seems to be the seismic source for spectral energy at 4.8 s and 10 s, which represent the Double Frequency and the Primary Frequency of the OMS, respectively. Concerning the 6 s peak, a cyclone near the British Isles could act as a seismic source. Seismic data from the first broadband array deployed on Stromboli showed surprisingly simple waveforms, indicating an initially contracting source mechanism. The analysis of particle motion and the application of seismic array techniques allowed the location of a seismic source in the shallow part of the volcano. Eruption parameters and seismic source characteristics of the April 5, 2003 Stromboli eruption have been estimated using different inversion approaches. The paroxysm was triggered by a shallow slow thrust-faulting dislocation event with a moment magnitude of Mw = 3.0 and possibly associated with a crack that formed previously by dike extrusion. At least one blow-out phase during the paroxysmal explosion could be identified from seismic signals with an equivalent moment magnitude of Mw = 3.7. It can be represented by a vertical linear vector dipole and two weaker horizontal linear dipoles in opposite direction, plus a vertical force. Seismic measurements performed during controlled and reproducible blow-out experiments with a gas volume entrapped in basaltic melt revealed the following: Monochromatic seismic signals suggest a blow-out in a more ductile regime, whereas broader frequency content indicates rupture in a more brittle environment. The longer the crucible, the weaker the seismic signals. An increase in pressure results in a stronger fragmentation, but not in a higher ejection velocity of the plug neither in a higher seismic amplitude. Even if the very long period observations like the tilt signal could not be simulated in the laboratory, the blow-out experiments simulate very well the short-period seismic signals recorded at Stromboli volcano