Дисертації з теми "Seismic source inversion"
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Fichtner, Andreas. "Full seismic waveform inversion for structural and source parameters." Diss., lmu, 2010. http://nbn-resolving.de/urn:nbn:de:bvb:19-114940.
Повний текст джерелаBrown, Vanessa. "Integration of seismic full waveform and controlle-source marine electromagnetic inversion." Institut de physique du globe (Paris), 2012. http://www.theses.fr/2012GLOB1201.
Повний текст джерелаTwardzik, Cedric. "Study of the earthquake source process and seismic hazards." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:c2553a3f-f6ce-46a0-9c47-d68f5957cdac.
Повний текст джерелаYordkayhun, Sawasdee. "2D and 3D Seismic Surveying at the CO2SINK Project Site, Ketzin, Germany: The Potential for Imaging the Shallow Subsurface." Doctoral thesis, Uppsala University, Department of Earth Sciences, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-9273.
Повний текст джерелаSeismic traveltime inversion, traveltime tomography and seismic reflection techniques have been applied for two dimensional (2D) and three dimensional (3D) data acquired in conjunction with site characterization and monitoring aspects at a carbon dioxide (CO2) geological storage site at Ketzin, Germany (the CO2SINK project). Conventional seismic methods that focused on investigating the CO2 storage and caprock formations showed a poor or no image of the upper 150 m. In order to fill this information gap, an effort on imaging the shallow subsurface at a potentially risky area at the site is the principal goal of this thesis.
Beside this objective, a seismic source comparison from a 2D pilot study for acquisition parameter testing at the site found a weight drop source suitable with respect to the signal penetration, frequency content of the data and minimizing time and cost for 3D data acquisition.
For the Ketzin seismic data, the ability to obtain high-quality images is limited by the acquisition geometry, source-generated noise and time shifts due to near-surface effects producing severe distortions in the data. Moreover, these time shifts are comparable to the dominant periods of the reflections and to the size of structures to be imaged. Therefore, a combination of seismic refraction and state-of-the-art processing techniques, including careful static corrections and more accurate velocity analysis, resulted in key improvements of the images and allowed new information to be extracted. The results from these studies together with borehole information, hydrogeologic models and seismic modeling have been combined into an integrated interpretation. The boundary between the Quaternary and Tertiary unit has been mapped. The internal structure of the Quaternary sediments is likely to be complicated due to the shallow aquifer/aquitard complex, whereas the heterogeneity in the Tertiary unit is due to rock alteration associated with fault zones. Some of the major faults appear to project into the Tertiary unit. These findings are important for understanding the potentially risky anticline crest and can be used as a database for the future monitoring program at the site.
Gallo, Antonella. "Inversion for slip on a finite fault and fast estimation of seismic parameters in the point source case." Doctoral thesis, Università degli studi di Trieste, 2012. http://hdl.handle.net/10077/7391.
Повний текст джерелаABSTRACT One of the principal goals of seismology is to infer the nature of an earthquake source from observations of seismic ground motion. This work shall discuss the seismic source both in the 2D finite-fault and in the point-source approximation. By inverting 3-component accelerograms the rupture history and the slip distribution for the Mw 6.3 earthquake occurred in central Italy on April 6, 2009 are determined. The method of linear programming is used for the inversion and the simplex method is applied to solve the linear programming problem (Das and Kostrov, 1994). All known parameters, such as crustal structure and station distribution are kept fixed and a large-enough fault area is considered. Physical constraints such as the positivity of the slip rates on the fault and a pre-assigned seismic moment are used to stabilize the solution. Using synthetic data with a checkerboard slip distribution shows that the obtainable spatial resolution is around 2 km. Observed records acquired from local stations of the national strong-motion network are inverted. Only data from rock stations distributed uniformly around the fault at epicentral distances less than 80 km are used. The accelerograms are filtered at 1 Hz and about 15 seconds of the signals are modelled. The obtained slip distribution shows a single major asperity and is in agreement with other similar studies of the L’Aquila earthquake. The main event of L’Aquila is used to validate a stable and automatic procedure implemented by SeiSRaM group (Dep. of Mathematics and Geosciences, University of Trieste) for the SE Alps transfrontier network to estimate in real time the seismic moment, moment magnitude and corner frequency of events recorded by broad-band velocimeters and accelerometers. The procedure has two steps: the first one consists in an interface with the Antelope system (a software that manages the network) from which pre-processed waveforms are retrieved. The second step consists in estimating the seismic moment and the corner frequency by spectral analysis. The S-wave train is identified through an automatic picking procedure of Antelope software or, if that procedure fails, through the estimates arrival times based on the travel-time. The transversal component of motion is used to minimize conversion effects. The analyzed frequency window is selected on the basis of the signal-to-noise ratio (SNR). The source spectrum is obtained by correcting the signals for geometrical spreading and intrinsic attenuation. For the latter, different relationships are tested for frequency-dependent Q value in order to characterize the anelastic proprieties of the seismic region. Source spectra for both velocity and displacement are computed and, following Andrews (1986), the seismic moment and the corner frequency are estimated. The procedure is successfully validated using the recordings of some recent strong earthquakes like Carnia 2002 (Mw=4.9), Bovec 2004 (Mw =5.1), Parma 2008 (Mw =5.4) and Aquila 2009 (Mw =6.3) and the recording of some minor events in the SE Alps area for which independent seismic moment and Mw estimates are available. Since one year the procedure is applied to events recorded by the National Accelerometric Network (RAN). The agreement between moment magnitudes estimated by the SeiSRaM procedure and the INGV local magnitudes is very good.
RIASSUNTO I terremoti sono fenomeni fisici molto complessi a partire dai processi di sorgente alla determinazione della magnitudo, argomenti fondamentali nelle indagini sismologiche. Questa tesi si propone di indagare i processi fisici degli eventi sismici. L’approccio è studiare la sorgente sismica del terremoto a partire dai dati delle registrazioni, 'decifrando' le informazioni contenute in esse con l’uso sia delle teorie fisiche che con modelli matematici. In questo lavoro si discute la sorgente sismica sia nel suo modello più semplice, il caso della sorgente puntiforme, sia nella sua descrizione realistica con dimensioni finite. Una descrizione teorica delle caratteristiche e delle rappresentazioni della sorgente estesa sono rappresentate nel Cap. 1. Sono descritti i fondamenti teorici che, sulla base di numerosi studi sperimentali, sembrano meglio descrivere gli eventi sismici, gli strumenti matematici che governano i processi di rottura, i modelli che rappresentano meglio la situazione fisica che sta alla base dei terremoti, quali il modello di Haskel ed il modello di Brune (1970) e l’approssimazione della sorgente estesa come somma di sorgenti puntiformi. Il tema centrale di questo studio riguarda la comprensione e la modellazione cinematica del processo di rottura di un terremoto su una faglia finita, attraverso l'inversione dei dati accelerometrici. L’inversione di dati simici permette di ottenere gran parte delle informazioni sul comportamento spazio-temporale del processo di rottura. L'approccio cinematico consente di interpretare le forme d’onda che si irradiano dalla sorgente in termini di spostamento relativo lungo il piano di faglia in funzione dello spazio e del tempo (la storia dello scorrimento). Usando il teorema di rappresentazione, lo spostamento registrato da una stazione durante un terremoto può essere espresso in termini della distribuzione di scorrimento sulla superficie di faglia. Assumendo che la faglia sia piana e la direzione di scorrimento costante, il problema può essere discretizzato, vincolato e ricondotto ad un sistema di equazioni lineare Ax=b (Cap. 2). La soluzione a questo problema è tutt’altro che banale. E’ ben noto che il problema è instabile e dal punto di vista computazionale questa instabilità è equivalente alla non unicità della soluzione. Quindi, per ottenere una soluzione definita vi è la necessità di inserire alcuni vincoli fisici nel processo di sorgente in aggiunta alla semplice richiesta di riprodurre i dati osservati (Das e Kostrov, 1990, Das e Suhadolc, 1996). Strumento fondamentale nella procedura di calcolo e cuore della procedura di inversione adottata in questa tesi, il metodo del simplesso viene introdotto nell’ambito dello studio della programmazione lineare e applicato ad un piccolo esempio esplicativo (Cap. 3). Seguendo la formulazione sviluppata da Das e Kostrov (1990,1994) si è applicata la procedura di inversione all’evento principale dell’Aquila avvenuto il 6 aprile 2009. Dopo una breve descrizione geologica dell’Aquila, della struttura utilizzata e del modello di sorgente adottato (Cap. 4) vengono presentati i risultati sia in termini di distribuzione del momento sismico sulla faglia sia in termini di confronto tra le forma d’onda reali e sintetiche (Cap. 5). E’ la prima volta che si utilizzano dati reali con il tempo assoluto. Questo ha portato non pochi problemi principalmente nella scelta del modello di velocità e nella scelta delle stazioni. Sono state considerate solo stazioni della Rete Accelerometrica Nazionale (RAN) su roccia con distanze epicentrali tra 20 km ed 80 km. Attraverso test sintetici e confrontando con quanto riportato in letteratura, è stato scelto il modello di sorgente che meglio si adatta ai dati disponibili. Tutte le inversioni sono state fatte imponendo vincoli fisici quali la casualità, la positività e il momento prefissato totale. Questi vincoli sono stati necessari per avere una soluzione più stabile. Sono stati investigati differenti modelli di faglia, differenti distribuzioni di stazioni e due modelli di velocità. I risultati migliori sono stati ottenuti considerando una faglia lunga 28 km a larga 12 km discretizzata in celle 2km per 2 km, e considerando solo le quattro stazioni situate sul tetto di faglia (Saraò et al.,1996). Il modello di velocità è quello proposto da Costa et al. (1992). La distribuzione del momento mostra somiglianze con i risultati ottenuti dell’inversione di dati sismici proposta da altri autori, confermando che la massima energia è nella parte SE della faglia. Nella seconda parte della tesi l’attenzione si è focalizzata sulla determinazione dei parametri di sorgente. Si è utilizzata la procedura implementata dal gruppo SeisRaM del Dipartimento di Matematica e Geoscienze, che stima in real-time il momento sismico, la magnitude da momento e la frequenza d’angolo. La determinazione della grandezza di un terremoto è un problema aperto. Esistono differenti scale di magnitudo e differenti metodi di calcolo, tanto da ottenere diversi valori per lo stesso evento, da parte dei diversi enti che li determinano. Nel Cap. 6 sono trattate le scale di magnitudo in uso ed in particolare la magnitudo da momento. Infine, sono descritti due metodi utilizzati per il calcolo in real-time della magnitudo da momento, tra cui il metodo di Andrews (1986) utilizzato nella procedura. Nel Cap. 7 dopo una descrizione della procedura automatica, si riportano la validazione ed i risultati. Questo metodo automatico stima in real-time i parametri di sorgente degli eventi delle Alpi sud orientali registrati dalla rete Transfrontaliera e da circa un anno anche degli eventi registrati dalla RAN. La procedura è stata validata sugli eventi recenti avvenuti in Italia e Slovenia: L’Aquila 2009, Parma 2008, Bovec 2004 e Carnia 2002. Il confronto della magnitudo da momento stimata della procedura in studio e quella calcolata con metodi di inversione da altri istituzioni è molto buono, dimostrando l’affidabilità e la robustezza di questo metodo. Questo è stato confermato dalla stima della magnitudo degli ultimi eventi avvenuti in Italia durante la scrittura finale di questa tesi: Verona, 24 gennaio 2012 e Reggio Emilia, 25 gennaio 2012. La magnitudo stimata in real-time dalla procedura è in ottimo accordo con quella stimata dall’INGV. Inoltre sia l’Agenzia sismologica della Slovenia, l’ARSO, che quella romena hanno richiesto di poter utilizzare questa procedura real-time. Questo lavoro spera di essere una fonte di utili suggerimenti nello studio dei processi di sorgente.
XXIV Ciclo
1979
Chen, Kejie [Verfasser], and Michael [Akademischer Betreuer] Weber. "Real-time GNSS for fast seismic source inversion and tsunami early warning / Kejie Chen ; Betreuer: Michael H. Weber." Potsdam : Universität Potsdam, 2016. http://d-nb.info/1218400633/34.
Повний текст джерелаChen, Kejie [Verfasser], and Michael H. [Akademischer Betreuer] Weber. "Real-time GNSS for fast seismic source inversion and tsunami early warning / Kejie Chen ; Betreuer: Michael H. Weber." Potsdam : Universität Potsdam, 2016. http://d-nb.info/1218400633/34.
Повний текст джерелаSen, Ali Tolga [Verfasser], and Torsten [Akademischer Betreuer] Dahm. "Inversion of seismic source parameters for weak mining-induced and natural earthquakes / Ali Tolga Sen ; Betreuer: Torsten Dahm." Potsdam : Universität Potsdam, 2014. http://d-nb.info/1218399031/34.
Повний текст джерелаSanchez, Reyes Hugo Samuel. "Inversion cinématique progressive linéaire de la source sismique et ses perspectives dans la quantification des incertitudes associées." Thesis, Université Grenoble Alpes (ComUE), 2019. http://www.theses.fr/2019GREAU026/document.
Повний текст джерелаThe earthquake characterization is a fundamental research field in seismology, which final goal is to provide accurate estimations of earthquake attributes. In this study field, various questions may rise such as the following ones: when and where did an earthquake happen? How large was it? What is its evolution in space and time? In addition, more challenging questions can be addressed such as the following ones: why did it occur? What is the next one in a given area? In order to progress in the first list of questions, a physical description, or model, of the event is necessary. The investigation of such model (or image) is the scientific topic I investigate during my PhD in the framework of kinematic source models. Understanding the seismic source as a propagating dislocation that occurs across a given geometry of an active fault, the kinematic source models are the physical representations of the time and space history of such rupture propagation. Such physical representation is said to be a kinematic approach because the inferred rupture histories are obtained without taking into account the forces that might cause the origin of the dislocation.In this PhD dissertation, I present a new hierarchical time kinematic source inversion method able to assimilate data traces through evolutive time windows. A linear time-domain formulation relates the slip-rate function and seismograms, preserving the positivity of this function and the causality when spanning the model space: taking benefit of the time-space sparsity of the rupture model evolution is as essential as considering the causality between rupture and each record delayed by the known propagator operator different for each station. This progressive approach, both on the data space and on the model space, does require mild assumptions on prior slip-rate functions or preconditioning strategies on the slip-rate local gradient estimations. These assumptions are based on simple physical expected rupture models. Successful applications of this method to a well-known benchmark (Source Inversion Validation Exercise 1) and to the recorded data of the 2016 Kumamoto mainshock (Mw=7.0) illustrate the advantages of this alternative approach of a linear kinematic source inversion.The underlying target of this new formulation will be the future uncertainty quantification of such model reconstruction. In order to achieve this goal, as well as to highlight key properties considered in this linear time-domain approach, I explore the Hamiltonian Monte Carlo (HMC) stochastic Bayesian framework, which appears to be one of the possible and very promising strategies that can be applied to this stabilized over-parametrized optimization of a linear forward problem to assess the uncertainties on kinematic source inversions. The HMC technique shows to be compatible with the linear time-domain strategy here presented. This technique, thanks to an efficient estimation of the local gradient of the misfit function, appears to be able to rapidly explore the high-dimensional space of probable solutions, while the linearity between unknowns and observables is preserved. In this work, I investigate the performance of the HMC strategy dealing with simple synthetic cases with almost perfect illumination, in order to provide a better understanding of all the concepts and required tunning to achieve a correct exploration of the model space. The results from this preliminary investigation are promising and open a new way of tackling the kinematic source reconstruction problem and the assessment of the associated uncertainties
Santos, Rúben José Chaves Miguel dos. "Modelação de processos de rotura sísmica através de dados de observação da deformação superficial." Doctoral thesis, Universidade de Évora, 2013. http://hdl.handle.net/10174/11790.
Повний текст джерелаBletery, Quentin. "Analyse probabiliste et multi-données de la source de grands séismes." Thesis, Nice, 2015. http://www.theses.fr/2015NICE4092/document.
Повний текст джерелаEarthquakes are the results of rapid slip on active faults loaded in stress by the tectonic plates motion. It is now establish - at least for large earthquakes - that the distribution of this rapid slip along the rupturing faults is heterogeneous. Imaging the complexity of such slip distributions is one the main challenges in seismology because of the potential implications on understanding earthquake genesis and the associated possibility to better anticipate devastating shaking and tsunami. To improve the imaging of such co-seismic slip distributions, three axes may be followed: increase the constraints on the source models by including more observations into the inversions, improve the physical modeling of the forward problem and improve the formalism to solve the inverse problem. In this PhD thesis, we explore these three axes by studying two recent major earthquakes: the Tohoku-Oki (Mw 9.0) and Sumatra-Andaman (Mw 9.1-9.3) earthquakes, which occured in 2011 and 2004 respectively
Silvennoinen, H. (Hanna). "3D structure of the crust and upper mantle beneath Northern Fennoscandian shield." Doctoral thesis, University of Oulu, 2015. http://urn.fi/urn:isbn:9789526210681.
Повний текст джерелаKim, Junkyoung. "Complex seismic sources and time-dependent moment tensor inversion." Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184841.
Повний текст джерелаPlasencia, Linares Milton Percy. "Lithospheric characteristics and seismic sources in the SCOTIA ARC through waveform inversion." Doctoral thesis, Università degli studi di Trieste, 2008. http://hdl.handle.net/10077/2687.
Повний текст джерелаThe Scotia Sea region is found between the south American and Antarctic plates and constitutes a complex area tectonics, characterized from numerous active processes and changes in the movement and in the configuration of the plates. The main tectonics characteristics of the Scotia Sea were object of different studies, nevertheless some details of the interactions tectonics, of the margin of plates and of their relative movement remain still uncertain. In this sense, the determination of the features of the lithosphere and the study of the focal mechanisms develop an important role to understand the geodynamic evolution of the area. This study proposes to use the present technologies for the inversion of wave- forms to the end of to obtain the source mechanisms for a series of earthquakes recorded in the proximity of the Antarctic Base Argentina Orcadas. The appli- cation of the method is possible thanks to the digital seismograms recorded from a regional network installed to leave from 1992 and that includes the Antarctic Seismographic Argentinean Italian Network (ASAIN) and other three seismo- graphic stations of the Global Seismographic Network (GSN) operating in the antarctic Peninsula, Tierra del Fuego and in the islands of the Scotia arc. Were analyzed and reproduced seven events that followed the earthquake of magnitude 7,6 Mw 4 August 2003 known in literature like Centenary Earthquake. The main unit of the study (Chapter 3) is preceded of two chapters dedicated respectively to a detailed description of the situation tectonics and the seismicity of the Scotia Sea region (Chapter 1) and the Italian-Argentinean seismographic network ASAIN with special attention for the response in frequency of the seismograph and the characterization of the seismic noise levels (Chapter 2). Like complement to the analysis of the focal mechanisms, applying the Omori’s law, it has determined the curve of temporal decay of the seismic se- quence recorded from the Orcadas station in sixty days following to the Cente- nary Earthquake.
XIX Ciclo
1960
Li, Ka Lok. "Location and Relocation of Seismic Sources." Doctoral thesis, Uppsala universitet, Geofysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-327038.
Повний текст джерелаHobson, Vessela. "First-arrival traveltime tomography of active-source data in the Kansanshi copper mine, northern Zambia." Thesis, Uppsala universitet, Geofysik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-398370.
Повний текст джерелаLiu, Qinya Stock J. M. "Spectral-element simulations of 3-D seismic wave propagation and applications to source and structural inversions /." Diss., Pasadena, Calif. : Caltech, 2006. http://resolver.caltech.edu/CaltechETD:etd-05262006-172954.
Повний текст джерелаCrusem, René. "Simulation de signaux sismiques et étude de sources nucléaires souterraines par inversion de moments." Châtenay-Malabry, Ecole centrale de Paris, 1986. http://www.theses.fr/1986ECAP0054.
Повний текст джерелаTEYSSONEYRE, VALERIE. "Inversion du tenseur des moments sismiques pour des seismes de magnitude moderee enregistres a des distances regionales." Université Joseph Fourier (Grenoble), 2001. http://www.theses.fr/2001GRE10017.
Повний текст джерелаHagos, Lijam Zemichael. "Earthquake Sources, the Stress Field and Seismic Hazard : A Study in Eritrea and its Surrounding." Doctoral thesis, Uppsala universitet, Geofysik, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-7292.
Повний текст джерелаCourboulex, Françoise. "Inversion spatio-temporelle de la source sismique a l'aide des fonctions de green empiriques : deconvolution par recuit simule et application a des seismes de faible magnitude." Paris 6, 1995. http://www.theses.fr/1995PA066059.
Повний текст джерелаLEBORGNE, SEBASTIEN. "Etude de la propagation des ondes de volume dans le manteau superieur sous l'europe et inversion du mecanisme a la source de seismes grecs et turcs." Paris 7, 1998. http://www.theses.fr/1998PA077243.
Повний текст джерелаWang, Hanchen. "Micro-seismic Imaging Using a Source Independent Waveform Inversion Method." Thesis, 2016. http://hdl.handle.net/10754/609461.
Повний текст джерелаMinkoff, Susan Elizabeth. "Multiparameter inversion and energy source estimation for a reflection seismic experiment." Thesis, 1995. http://hdl.handle.net/1911/16858.
Повний текст джерелаAlTheyab, Abdullah. "Imaging of Scattered Wavefields in Passive and Controlled-source Seismology." Diss., 2015. http://hdl.handle.net/10754/595157.
Повний текст джерелаFichtner, Andreas [Verfasser]. "Full seismic waveform inversion for structural and source parameters / vorgelegt von Andreas Fichtner." 2009. http://d-nb.info/1003285929/34.
Повний текст джерелаMustac, Marija. "Hierarchical Bayesian Inversion for the Point Source Moment Tensor: Method and Applications." Phd thesis, 2016. http://hdl.handle.net/1885/113632.
Повний текст джерелаCirella, A. "Joint Inversion of GPS and Strong Motion Data for Earthquake Rupture Models." Thesis, 2008. http://hdl.handle.net/2122/5657.
Повний текст джерелаIstituto Nazionale di Geofisica e Vulcanologia
Unpublished
3.1. Fisica dei terremoti
open
Liu, Ruo-Shan, and 劉若珊. "Ambient seismic noise analysis: Origin of noise source and tomographic inversion for lithospheric velocity structure offshore eastern Taiwan." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/242wv8.
Повний текст джерела國立臺灣大學
海洋研究所
104
We apply ambient noise analysis to continuous seismic waveform data recorded by ocean-bottom seismometers (OBS) deployed in the Huatung Basin and adjacent regions off the east coast of Taiwan. Taiwan is a young and active orogenic belt resulting from the oblique subduction and collision between the Eurasian Plate and the Philippine Sea Plate. Sitting on the westernmost edge of the Philippine Sea Plate, the Huatung Basin is directly involved in the subduction-collision processes. The structural characteristics of the basin provide important constraints not only on its own history but the tectonic evolution in this complex region. We first analyze the noise signals by stacking cross-correlation functions from station pairs between OBS stations and between land and OBS stations. We find that, unsurprisingly, the noise power of the offshore OBS stations is larger than that of onshore stations. Further, we integrate the OBS data with selected land station data along the east coast, deriving Rayleigh wave Green’s functions from cross-correlation between all available station pairs. We measure phase velocity dispersion at periods from 4 to 20 sec, and invert for 2-D anisotropic phase velocity maps based on a wavelet-based multi-scale inversion scheme. Our results show that, at periods 12-20 s, significant seismic anisotropy is present in the Huatung Basin close to Taiwan’s southeast coast, with fast direction sub-parallel to the direction of convergence. On the other hand, to the north across the Ryukyu trench, anisotropy becomes weaker and the fast direction appears to rotate clockwise toward NW-SE to N-S directions. These characteristics represent the property of the mantle lithosphere of the Huatung Basin, implying for current influence of asthenospheric flow due to currently the PSP plate motion.
Lorimer, T. "Non-Linear tomographic inversion of active source seismic data: An investigation of the basement structure of Eastern Tasmania." Thesis, 2007. https://eprints.utas.edu.au/12995/1/Front_Lorimer_T_Hons_2007.pdf.
Повний текст джерелаSpagnuolo, E. "Evoluzione della trazione dinamica sulla faglia durante i forti terremoti." Thesis, 2006. http://hdl.handle.net/2122/10120.
Повний текст джерелаUniversità degli studi di Roma La Sapienza, Istituto Nazionale di Geofisica e Vulcanologia
Unpublished
4T. Fisica dei terremoti e scenari cosismici
open
Stramondo, S. "Seismic Source Quantitative Parameters Retrieval from InSAR Data and Neural Networks." Thesis, 2007. http://hdl.handle.net/2122/3043.
Повний текст джерелаTor Vergata University
Unpublished
open
Yelisetti, Subbarao. "Seismic structure, gas hydrate, and slumping studies on the Northern Cascadia margin using multiple migration and full waveform inversion of OBS and MCS data." Thesis, 2014. http://hdl.handle.net/1828/5719.
Повний текст джерелаGraduate
0373
0372
0605
subbarao@uvic.ca
Liu, Qinya. "Spectral-Element Simulations of 3-D Seismic Wave Propagation and Applications to Source and Structural Inversions." Thesis, 2006. https://thesis.library.caltech.edu/2115/1/thesis.pdf.
Повний текст джерелаThis thesis presents a concise introduction to the spectral-element method and its applications to the simulation of seismic wave propagation in 3-D earth models. The spectral-element method is implemented in the regional scale for a 3-D integrated southern California velocity model. Significantly better waveform fits are achieved for the 3-D synthetics calculated compare to the 1-D synthetics generated from the 1-D standard southern California model, especially for many basin stations where strong amplifications are observed due to the very low wave-speed sediments. A hypothetical earthquake rupturing from northeast to southwest at the southern end of the San Andreas fault is simulated to improve our understanding of the seismic hazards in the Salton Trough region.
With the improved 3-D Green's function, we perform source inversions for both the source mechanisms and event depths of $M_w geq 3.5$ earthquakes in southern California. The inversion results generally agree well with the results obtained by other traditional methods, but with significantly more stations used in the inversions. Time shifts are generally required to align the data and the synthetics, which provides a great dataset for the improvement of the 3-D velocity models in southern California.
We use the adjoint method to formulate the tomographic inverse problem based upon a 3-D initial model. We calculate the sensitivity kernels, a key component of the tomographic inversion, that relate the perturbations of observations to the perturbations of the model parameters. These kernels are constructed by the interaction of the regular forward wavefield and the adjoint wavefield generated by putting the time-reversed signals at the receivers as simultaneous adjoint sources. We compute the travel-time sensitivity kernels for typical phases in both regional and global problems for educational purposes, and outline the procedures of applying the conjugate-gradient method to solve both source and structural inversion problems.