Добірка наукової літератури з теми "Urban seismology"

Since the Nobi Earthquake of 1891, seismology, engineering seismology, earthquake engineering, structural engineering and sciences which are related to the phenomena of earthquakes were developed in Japan. Especially pure sciences and engineering made great advances individually. However, actual earthquake damage has not yet ceased to exist, and this damage leads the loss of a great number of human lives. Undeveloped areas and not so important buildings have always suffered these disasters. From worldwise point of view, there is a more serious problem, sometimes more than 10,000 people are killed by an earthquake. The importance of these sciences and engineering is centered in such problems, but at their present stage of development they can not solve these serious problems. Primarily because there are many problems regarding the economical conditions. Seismic microzoning has its purpose in the solution of the serious problems mentioned above. The results of seismic microzoning should cover whole areas and structures, for saving money in construction and to minimize the danger posed to human life. Also seismic microzoning works are related to the disaster prevention programs of various areas. Investigations into seismic microzoning are mainly related to the field of engineering seismology and its applications are in earthquake engineering, but fundamental investigations and applications can not be separated, they are closely related. Thus difficult points still exist, because only a few investigators have interests in the applications of seismic microzoning work. In this paper the author tries to explain the theoretical background and the technique of application of seismic microzoning which developed mainly in Japan. But these theoretical and technical results are not yet completed, and the facts interpreted from the strong motion seismograms and other results of field observations will correct these conclusions.

Urban seismology has gained scientific interest with the development of seismic ambient noise monitoring techniques and also for being a useful tool to connect society with the Earth sciences. The interpretation of the sources of seismic records generated by sporting events, traffic, or huge agglomerations arouses the population’s curiosity and opens up a range of possibilities for new applications of seismology, especially in the area of urban monitoring. In this contribution, we present the analysis of seismic records from a station in the city of Brasilia during unusual episodes of silencing and noisy periods. Usually, cultural noise is observed in high-fequency bands. We showed in our analysis that cultural noise can also be observed in the low-frequency band, when high-frequency signal is attenuated. As examples of noisy periods, we have that of the Soccer World Cup in Brazil in 2014, where changes in noise are related to celebrations of goals and the party held by FIFA in the city, and the political manifestations in the period of the Impeachment trial in 2016, which reached the concentration of about 300,000 protesters. The two most characteristic periods of seismic silence have been the quarantine due to the COVID-19 pandemic in 2020, and the trucker strike that occurred across the country in 2018, both drastically reducing the movement of people in the city.

AbstractThe spatial distribution of urban vegetation cover is strongly related to climatological conditions, which play a vital role in urban cooling via shading and reducing ground surface temperature and effective strategy in mitigation urban heat island. Based on the Landsat satellite images, the quantitative normalized difference vegetation index (NDVI) was spatially mapped at two times for each year during 2008, 2013, 2019 in Baghdad. The NDVI values ranged from −1 to +1 with considering values larger than 0.2 indicate the dense healthy vegetation. In this study, the fractional areas of NDVI >0.2 were computed with their percentage. The responses of the NDVI during the growing seasons to two climate indices (i.e., air temperature and precipitation) were investigated. These climatic data obtained from the Iraqi Meteorological Organization and Seismology for the aforementioned years were used to explore the potential correlations between seasonal NDVI and above climate variables. The result shows that NDVI-derived vegetation growth patterns were highly correlated with their recording during the current growth seasons.

Abstract Strong ground-motion records are the primary input data in earthquake engineering studies to improve understanding of seismic hazard and risk. As the overseer of the Iran Strong Motion Network (i1-net), the Road, Housing, and Urban Development Research Center occupies the leading position in this field in the country. With more than 1260 active accelerometers and a collection of over 14,129 earthquake recordings since 1973, the Iran Strong Motion Network is the major Iranian source of information for engineering seismology and earthquake engineering. The present article describes the current status and developments of the i1-net in the last 46 yr.

The proliferation of megacities in many developing countries, and their location in areas where they are exposed to a high risk from large earthquakes, coupled with a lack of preparation, demonstrates the requirement for improved capabilities in hazard assessment, as well as the rapid adjustment and development of land-use planning. In particular, within the context of seismic hazard assessment, the evaluation of local site effects and their influence on the spatial distribution of ground shaking generated by an earthquake plays an important role. It follows that the carrying out of earthquake microzonation studies, which aim at identify areas within the urban environment that are expected to respond in a similar way to a seismic event, are essential to the reliable risk assessment of large urban areas. Considering the rate at which many large towns in developing countries that are prone to large earthquakes are growing, their seismic microzonation has become mandatory. Such activities are challenging and techniques suitable for identifying site effects within such contexts are needed. In this dissertation, I develop techniques for investigating large-scale urban environments that aim at being non-invasive, cost-effective and quickly deployable. These peculiarities allow one to investigate large areas over a relative short time frame, with a spatial sampling resolution sufficient to provide reliable microzonation. Although there is a negative trade-off between the completeness of available information and extent of the investigated area, I attempt to mitigate this limitation by combining two, what I term layers, of information: in the first layer, the site effects at a few calibration points are well constrained by analyzing earthquake data or using other geophysical information (e.g., shear-wave velocity profiles); in the second layer, the site effects over a larger areal coverage are estimated by means of single-station noise measurements. The microzonation is performed in terms of problem-dependent quantities, by considering a proxy suitable to link information from the first layer to the second one. In order to define the microzonation approach proposed in this work, different methods for estimating site effects have been combined and tested in Potenza (Italy), where a considerable amount of data was available. In particular, the horizontal-to-vertical spectral ratio computed for seismic noise recorded at different sites has been used as a proxy to combine the two levels of information together and to create a microzonation map in terms of spectral intensity ratio (SIR). In the next step, I applied this two-layer approach to Istanbul (Turkey) and Bishkek (Kyrgyzstan). A similar hybrid approach, i.e., combining earthquake and noise data, has been used for the microzonation of these two different urban environments. For both cities, after having calibrated the fundamental frequencies of resonance estimated from seismic noise with those obtained by analysing earthquakes (first layer), a fundamental frequency map has been computed using the noise measurements carried out within the town (second layer). By applying this new approach, maps of the fundamental frequency of resonance for Istanbul and Bishkek have been published for the first time. In parallel, a microzonation map in terms of SIR has been incorporated into a risk scenario for the Potenza test site by means of a dedicated regression between spectral intensity (SI) and macroseismic intensity (EMS). The scenario study confirms the importance of site effects within the risk chain. In fact, their introduction into the scenario led to an increase of about 50% in estimates of the number of buildings that would be partially or totally collapsed. Last, but not least, considering that the approach developed and applied in this work is based on measurements of seismic noise, their reliability has been assessed. A theoretical model describing the self-noise curves of different instruments usually adopted in microzonation studies (e.g., those used in Potenza, Istanbul and Bishkek) have been considered and compared with empirical data recorded in Cologne (Germany) and Gubbio (Italy). The results show that, depending on the geological and environmental conditions, the instrumental noise could severely bias the results obtained by recording and analysing ambient noise. Therefore, in this work I also provide some guidelines for measuring seismic noise.
Aufgrund des enormen Wachstums neuer Megastädte und deren Vordringen in gefährdete Gebiete auf der einen Seite sowie der mangelnden Erdbebenvorsorge in vielen Entwicklungsländern auf der anderen Seite sind verbesserte Verfahren für die Beurteilung der Gefährdung sowie eine rasche Umsetzung bei der Raumplanung erforderlich. Im Rahmen der seismischen Gefährdungsabschätzung spielt insbesondere die Beurteilung lokaler Standorteffekte und deren Einfluss auf die durch ein Erdbeben verursachte räumliche Verteilung der Bodenerschütterung eine wichtige Rolle. Es ist daher unabdingbar, mittels seismischer Mikrozonierungsstudien diejenigen Bereiche innerhalb dicht besiedelter Gebiete zu ermitteln, in denen ein ähnliches Verhalten im Falle seismischer Anregung erwartet wird, um daraus eine zuverlässige Basis bei der Risikoabschätzung großer städtischer Gebiete zu erhalten. Aufgrund des schnellen Wachstums vieler Großstädte in Entwicklungsländern ist eine seismische Mikrozonierung zwingend erforderlich, stellt aber auch eine große Herausforderung dar; insbesondere müssen Verfahren verfügbar sein, mit deren Hilfe rasch eine Abschätzung der Standorteffekte durchgeführt werden kann. In der vorliegenden Arbeit entwickle ich daher Verfahren für die Untersuchung in Großstädten, die darauf abzielen, nicht-invasiv, kostengünstig und schnell durchführbar zu sein. Damit lassen sich innerhalb eines relativ kurzen Zeitraums große Gebiete untersuchen, falls der räumlichen Abstand zwischen den Messpunkten klein genug ist, um eine zuverlässige Mikrozonierung zu gewährleisten. Obwohl es eine gegenläufige Tendenz zwischen der Vollständigkeit aller Informationen und der Größe des untersuchten Gebiets gibt, versuche ich, diese Einschränkung durch Verknüpfung zweier Informationsebenen zu umgehen: In der ersten Ebene werden die Standorteffekte für einige Kalibrierungspunkte durch die Analyse von Erdbeben oder mittels anderer geophysikalischer Datensätze (z.B. Scherwellengeschwindigkeitsprofile) bestmöglich abgeschätzt, in der zweiten Ebene werden die Standorteffekte durch Einzelstationsmessungen des seismischen Rauschens für ein größeres Gebiet bestimmt. Die Mikrozonierung erfolgt hierbei mittels spezifischer, fallabhängiger Parameter unter Berücksichtigung eines geeigneten Anknüpfungspunktes zwischen den beiden Informationensebenen. Um diesen Ansatz der Mikrozonierung, der in dieser Arbeit verfolgt wurde, zu präzisieren, wurden in Potenza (Italien), wo eine beträchtliche Menge an Daten verfügbar war, verschiedene Verfahren untersucht. Insbesondere kann das Spektralverhältnis zwischen den horizontalen und vertikalen Seismometerkomponenten, welche für das seismische Rauschen an mehreren Orten aufgenommen wurde, als eine erste Näherung für die relative Verstärkung der Bodenbewegung verwendet werden, um darauf aufbauend die beiden Informationsebenen zu verknüpfen und eine Mikrozonierung hinsichtlich des Verhältnisses der spektralen Intensität durchzuführen. Anschließend führte ich diesen Zwei-Ebenen-Ansatz auch für Istanbul (Türkei) und Bischkek (Kirgisistan) durch. Für die Mikrozonierung dieser beiden Städte habe ich denselben Hybridansatz, der Daten von Erdbeben und von seismischem Rauschen verbindet, verwendet. Für beide Städte wurde nach Gegenüberstellung der Resonanzfrequenz des Untergrunds, die zum einen mit Hilfe des seismischen Rauschens, zum anderen durch Analyse von Erdbebendaten bestimmt worden ist (erste Ebene), eine Karte der Resonanzfrequenz unter Verwendung weiterer Messungen des seismischen Rauschens innerhalb des Stadtgebiets erstellt (zweite Ebene). Durch die Anwendung dieses neuen Ansatzes sind vor kurzem zum ersten Mal auch Karten für die Resonanzfrequenz des Untergrunds für Istanbul und Bischkek veröffentlicht worden. Parallel dazu wurde für das Testgebiet in Potenza eine auf dem spektralen Intensitätsverhältnis (SIR) basierende Mikrozonierungskarte in ein Risikoszenario mittels der Regression zwischen SIR und makroseismischer Intensität (EMS) integriert. Diese Szenariostudie bestätigt die Bedeutung von Standorteffekten innerhalb der Risikokette; insbesondere führt deren Einbeziehung in das Szenario zu einem Anstieg von etwa 50% bei der Zahl der Gebäude, für die ein teilweiser oder gar vollständiger Zusammenbruch erwartet werden kann. Abschließend wurde der im Rahmen dieser Arbeit entwickelte und angewandte Ansatz auf seine Zuverlässigkeit geprüft. Ein theoretisches Modell, das zur Beschreibung des Eigenrauschens verschiedener Instrumente, die in der Regel in Mikrozonierungsstudien (z. B. in Potenza, Istanbul und Bischkek) zum Einsatz kommen, wurde untersucht, und die Ergebnisse wurden mit Daten verglichen, die vorher bereits in Köln (Deutschland) und Gubbio (Italien) aufgenommen worden waren. Die Ergebnisse zeigen, dass abhängig von den geologischen und umgebenden Bedingungen das Eigenrauschen der Geräte die Ergebnisse bei der Analyse des seismischen Rauschens stark verzerren kann. Deshalb liefere ich in dieser Arbeit auch einige Leitlinien für die Durchführung von Messungen des seismischen Rauschens.

Events or forces of nature with catastrophic consequences, or "natural disasters," have increased in both frequency and force due to climate change and increased urbanization in climate-sensitive areas. To create capacity to face these dangers, an entity must first quantify the threat and translate scientific knowledge on nature into comprehensible estimates of cost and loss. These estimates equip those at risk with knowledge to enact policy, formulate mitigation plans, raise awareness, and promote preparedness in light of potential destruction. Hazards-United States, or Hazus, is one such tool created by the federal government to estimate loss from a variety of threats, including earthquakes, hurricanes, and floods. Private and governmental agencies use Hazus to provide information and support to enact mitigation measures, craft plans, and create insurance assessments; hence the results of Hazus can have lasting and irreversible effects once the hazard in question occurs. This thesis addresses this problem and sheds light on the obvious and deterministic failings of Hazus in the context of the probable earthquake in Portland, OR; stripping away the tool's black box and exposing the grim vulnerabilities it fails to account for. The purpose of this thesis is twofold. First, this thesis aims to examine the critical flaws within Hazus and the omitted vulnerabilities particular to the Portland region and likely relevant in other areas of study. Second and more nationally applicable, this thesis intends to examine the influence Hazus outputs can have in the framing of seismic risk by the non-expert public. Combining the problem of inadequate understanding of risk in Portland with the questionable faith in Hazus alludes to a larger, socio-technical situation in need of attention by the academic and hazard mitigation community. This thesis addresses those issues in scope and adds to the growing body of literature on defining risk, hazard mitigation, and the consequences of natural disasters to urban environments.

La ville de Quito, capitale de l’Équateur est située dans une vallée andine à 2800 mètres d’altitude entourée de volcans. Cette ville qui accueille environ 2 millions d’habitant est sujette à l’occurrence de séismes importants. Elle est de plus particulièrement vulnérable puisqu’aucun code parasismique n’est pour le moment utilisé pour les constructions. L’étude de l’aléa et du risque sismique y est donc primordiale. Trois type de séismes menacent la ville : un séisme proche de magnitude modérée (M~6.5) qui aurait lieu sur le réseau de faille de Quito, un séisme plus lointain qui pourrait avoir une magnitude plus élevée (M~7.5) venant de la cordillère et enfin un séisme de subduction venant de la côte à plus de 170 km de distance, dont la magnitude pourrait très élevée (M> 8.5). C’est ce troisième type de séisme qui a frappé l’Équateur le 16 avril 2016 (séisme de Pedernales, Mw 7.8). Ce séisme a causé des dégâts très importants sur la côte et plusieurs centaines de victimes. Il a fait trembler également la ville de Quito mais n’a causé aucun dommage. Qu’en serait-il pour un séisme plus fort ? Est-ce que l’effet d’amplification des ondes sismiques dû au bassin sédimentaire de Quito pourrait, comme cela a été le cas en 1985 dans le bassin de Mexico, engendrer des valeurs de mouvement du sol très fortes causant des dégâts importants ? Est-ce que des séismes de plus faible magnitude mais plus proches pourraient menacer la ville de façon plus importante ? Ces questions scientifiques sont au cœur des préoccupations de ce sujet de thèse, qui est lui-même inclus dans un grand projet d’étude de la zone Équateur-Chili mené conjointement par l’Institut de Géophysique de Quito, et des chercheurs Français des laboratoires Géoazur, ISTerre, CEREMA et IFSTTAR. Objectifs de la thèse : Comprendre, caractériser et simuler les mouvements du sol dans la ville de Quito, en prenant en compte les effets de résonance du bassin (i.e. topographie de la base du bassin, remplissage alluvionnaire), ainsi que ceux dus à la forte topographie environnante. Réaliser des simulations de séismes futurs probables. Données disponibles (non encore exploitées): Enregistrements du bruit de fond par 20 stations large-bande dans et autour du bassin pendant 6 mois (la campagne de mesure sera menée de juillet à décembre 2017. Enregistrements de petits séismes sur le réseau accélérométrique de Quito (RENAQ) depuis 2010 Enregistrements du séisme de Pedernales et de ses principales répliques sur le réseau RENAQ Méthodologie : Corrélation de bruit de fond pour estimer des fonctions de Green inter-stations, en s’appuyant sur les données géologiques et géotechniques existantes. Autres techniques d’inversion (e.g. fonctions récepteur, étude d'ondes converties sur l'interface sédiments/socle) envisagées en fonction de la qualité des fonctions de Green estimées. Simulation basse fréquence en utilisant les fonctions de Green obtenues par intercorrélation du bruit Simulations haute fréquence par méthode hybrides utilisant des fonctions de Green empiriques (c’est-à-dire les enregistrements de petits séismes)
The city of Quito (Ecuador's capital) is located in an Andean valley at 2800 meters above sea level. Surrounded by volcanoes, this city of approximately 2 million inhabitants is prone to major earthquakes, and it is particularly vulnerable since no seismic code is formally used for constructions. The study of the hazard and the seismic risk is, therefore, essential. Three types of earthquakes threaten the city: a) a close earthquake of moderate magnitude (M ~ 6.5), which would occur on the Quito fault system, b) a more distant earthquake which could have a higher magnitude (M ~ 7.5) coming from the cordillera, and c) finally a subduction earthquake coming from the coastline more than 170 km away, the magnitude of which could be very high (M> 8.5). This third type of earthquake struck Ecuador on April 16, 2016 (Pedernales earthquake, Mw 7.8). Pedernales earthquake caused very significant damage to the coast region and several hundred victims. It also made the city of Quito tremble but caused no damage. What about a stronger earthquake? Could the seismic wave amplifying effect due to the Quito sedimentary basin, as was the case in 1985 in the Mexico City basin, generate very strong ground motion values causing significant damage? Could smaller magnitude but closer earthquakes threaten the city more seriously? These scientific questions are at the heart of this thesis subject's concerns, which is included in a major study project of the Ecuador-Chile zone carried out jointly by the Institute of Geophysics of Quito and French researchers from GeoAzur, ISTerre, CEREMA, and IFSTTAR laboratories. Objectives of the thesis: Understand, characterize, and simulate ground movements in Quito's city, taking into account the effects of basin resonance (i.e., the geometry of the basin's bedrock, alluvial filling) well as those due to the strong surrounding topography. Carry out simulations of likely future earthquakes. Available data (not yet used): Background noise recordings by 20 broadband stations in and around the basin for six months (the measurement campaign will be carried out from July to December 2017). Small earthquakes recordings on the Quito accelerometric network (RENAQ) since 2010. Recordings of the Pedernales earthquake and its main aftershocks on the RENAQ network Methodology : Seismic noise cross-correlation to estimate inter-station Green's functions, relying on existing geological and geotechnical data. Other inversion techniques (e.g., receiver functions, the study of converted waves on the sediment/bedrock interface) considered depending on the quality of the estimated Green's functions. Low-frequency stimulation using Green's functions obtained by cross-correlation of noise and high-frequency simulations using empirical Green's functions (i.e., recordings of small earthquakes)

The issues associated with this study are both physical and intellectual, as are the factors in urban development. The correlation of known data from inscriptions (epigraphy), literary references (ancient history and more recent government and church documents), evidence from destroyed and rebuilt buildings (archaeology), and modern scientific and technical findings (several kinds of engineering and subfields of geology such as seismology and sedimentology) can give a more complete picture of each city’s development than does one kind of information alone. Most of the necessary site-specific studies, however, have not been done. Our problem parallels the study of global warming, where precise records of weather events have been kept for less than 200 years. Urban elements must be studied by experts in that building type and in social expression. Ramparts need more study by historians of warfare, theaters by scholars of drama and literature, stadia by those who study the history of sports, plumbing by hydraulic, civil, and fluids engineers, and temples by historians of comparative religion. Insights into institutional and political aspects of ancient studies and the historiography of all the disciplines involved in ancient studies would be both useful and fascinating (Kardulias 1994). The benefits and difficulties of interdisciplinary research are clearer now to us than when we started. In considering the physical setting and geological processes in the Mediterranean area, is description sufficient or should scholars strive for explanation, even if this involves theory building? “In much of art history and classical archaeology traditional practices have continued without explicit theoretical support” (McNally 1985; but cf. Preziosi 1989). The theorists of archaeology and urban history desire comprehensive and precise theories—even in the absence of enough data to make that possible. Some data may be rescued by followers of one discipline after being ignored or thrown out by followers of another. The awareness of theoretical difficulty is part of the increase in consciousness typical of the second half of the twentieth century when we began to question the nature of both knowledge and culture.