Download or read book Rupture Imaging of Large Earthquakes with a Poststack Isochrone Migration Method written by Frank Krüger and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Imaging the Rupture Processes of Earthquakes Using the Relative Back Projection Method written by Hao Zhang and published by Springer. This book was released on 2017-12-27 with total page 127 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis adopts the relative back-projection method to dramatically reduce “swimming” artifacts by identifying the rupture fronts in the time window of a reference station; this led to a faster and more accurate image of the rupture processes of earthquakes. Mitigating the damage caused by earthquakes is one of the primary goals of seismology, and includes saving more people’s lives by devising seismological approaches to rapidly analyze an earthquake’s rupture process. The back-projection method described in this thesis can make that a reality.
Download or read book Reconstruction of the Earthquake Rupture Process Through Coherent Teleseismic Imaging and Statistical Modeling written by Marina Corradini and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Many studies have attempted to illuminate rupture complexities of large earthquakes through the use of coherent imaging techniques such as back-projection (BP). Recently, Fukahata et al. (2013) suggested that, from a theoretical point of view, the BP image of the rupture is related to the slip motion on the fault. However, the quantitative relationship between the BP images and the physical properties of the earthquake rupture process still remains unclear.Our work aims at clarifying how BP images of the radiated wavefield can be used to infer spatial heterogeneities in slip and rupture velocity along the fault. We simulate different rupture processes using a line source model. For each rupture model, we calculate synthetic seismograms at three teleseismic arrays and we apply the BP technique to identify the sources of high-frequency (HF) radiation. This procedure allows for the comparison of the BP images with the originating rupture model, and thus the interpretation of HF emissions in terms of along-fault variation of the three kinematic parameters: rise time, final slip, rupture velocity. Our results show that the HF peaks retrieved from BP analysis are most closely associated with space-time heterogeneities of slip acceleration. We verify our findings on two major earthquakes that occurred 9 years apart on the strike-slip Swan Islands fault: the Mw 7.3 2009 and the Mw 7.5 2018 North of Hondurasearthquakes. Both events followed a simple linear geometry, making them suitable for comparison with our synthetic approach. Despite the simple geometry, both slip-rate functions are complex, with several subevents. Our preliminary results show that the BP image of HF emissions allows to estimate a rupture length and velocity which are compatible with other studies and that strong HF radiation corresponds to the areas of large variability of the moment-rate function. An outstanding question is whether one can use the BP image of the earthquake to retrieve the kinematic parameters along the fault. We build on the findings obtained in the synthetic examples by training a neural network model to directly predict the kinematic parameters along the fault, given an input BP image. We train the network on a large number of different synthetic rupture processes and their BP images, with the goal of identifying the statistical link between HF radiation and rupture kinematic parameters. Our results show that the neural network applied to the BP image of the earthquake is able to predict the values of rise time and rupture velocity along the fault, as well as thecentral position of the heterogeneity, but not the absolute slip values, to which the HF BP approach is relatively insensitive. Our work sheds some light on the gap currently existing between the theoretical description of the generation of HF radiation and the observations of HF emissions obtained by coherent imaging techniques, tackling possible courses of action and suggesting new perspectives.
Download or read book The Rupture Process of Large Earthquakes Along Convergent Margins written by Charles Hershey Estabrook and published by . This book was released on 1992 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Earthquake Rupture Imaging and Multiscale Stress Drop Estimation written by Bettina P. Allmann and published by ProQuest. This book was released on 2008 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: Investigation of earthquake source parameters is important for better understanding of the physics behind earthquakes, which is essential for mitigating the hazards of destructive earthquakes. This dissertation explores several different aspects of source parameter estimation. First, I image the rupture process of the 2004 M6.0 Parkfield earthquake in three dimensions using a waveform back-projection method. I identify a distinct secondary high-frequency phase that radiated from a point about 13 km northwest of the hypocenter. Together with existing slip model inversions of the Parkfield earthquake, these results constrain several physical properties of the rupture process. Second, I use an iterative least-squares approach on both local and global seismic data to isolate source spectra from attenuation and near-station site effects and apply an empirical Green's function correction for near-source attenuation. Brune-type stress drop estimates for small earthquakes in the Parkfield area and for moderate to large earthquakes worldwide range from 0.1 to 50 MPa, with robust lateral variations in average stress drop. In Parkfield some of these variations change temporally after the 2004 M6.0 Parkfield earthquake. On a global scale, the stress drop variations are usually confined to specific plate boundaries or tectonic regimes. The highest average stress drops occur for oceanic transform fault earthquakes and other strike-slip events. Intraplate events have a factor of two higher average stress drops than interplate events. Stress drops of both small earthquakes in Parkfield and larger global earthquakes show no dependence on moment. Our stress-drop estimates, combined with other published results, provide strong evidence that earthquakes exhibit self-similarity over most of the instrumentally observable magnitude range. Finally, using the spectral separation method to discriminate between natural seismicity and man-made explosions, I find that the best single waveform discriminant for data recorded in southern California is the RMS-misfit between quarry blast spectra and an w-2 source model.
Download or read book Experiments in Imaging Rupture Properties and Early Aftershocks of Large Earthquakes written by Peter M. Shearer and published by . This book was released on 2005* with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Rupture Characteristics of Large Earthquakes written by and published by . This book was released on 2015 with total page 404 pages. Available in PDF, EPUB and Kindle. Book excerpt: The occurrence of many large and/or destructive global earthquakes over the past ten years has provided unprecedented seismic, geodetic, and tsunami recordings that reveal complex rupture processes advancing our understanding of earthquake physics. This thesis research has focused on seismological analysis of recent large earthquakes to extract observational insights that address two fundamental questions, "how do great earthquake rupture?", and "what controls large earthquakes?". We approach these two questions by providing an improved seismological understanding of large earthquake rupture processes, exploring the variation of kinematic source parameters, and placing the ruptures into the context of tectonic plate motions that drive the deformation. Given the great diversity of earthquakes, various seismic tools have been explored to give a better robust characterization of large earthquake ruptures. It includes W-phase point source inversion, back projection of seismic array data to map the space-time distribution of high-frequency coherent seismic radiation, determination of broadband source spectra and radiated energy, waveform inversion for co-seismic finite-source slip distribution, and forward modeling of and joint inversion with tsunami and GPS data. By applying these methods, I have studied large events located in different areas, including 1) megathrusts (subduction zone plate boundaries) along the Japan trench, Middle American Trench, and globally; 2) the large transform fault boundary near Scotia-Sea-Antarctic plate boundary, and 3) intraplate events in subducted slabs near the Philippine trench, at intermediate depth (70-300 km) beneath Rat Island earthquake and in the mantle transition zone (300-700 km) beneath Sea of Okhotsk and Ogasawara Islands. The controlling parameters for earthquake-related hazards (e.g. tsunami and strong ground shaking) and earthquake physical mechanisms (e.g. brittle failure, thermal weakening process, stress transfer) have been investigated with an emphasis on the frequency-dependence seismic radiation.
Download or read book Space time Rupture Properties of Large Earthquakes written by Jeffrey Joseph McGuire and published by . This book was released on 2000 with total page 179 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Rupture Propagation Imaging Across Scales from Large Earthquakes to Microseismic Events written by Jonas T. Folesky and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book AutoBATS and 3D MUSIC New Approaches to Imaging Earthquake Rupture Behaviors written by Pei-Ru Jian and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the kinematic earthquake rupture studies from moment tenor to spatial-temporal rupture imaging. For real-time seismic hazard monitoring, the new stable automatic moment tensor (AutoBATS) algorithm is developed and implemented for the real-time MT reports by the Taiwan Earthquake Science Information System (TESIS). In order to understand the rupture behavior of the 2013 Mw 8.3 Okhotsk deep earthquake sequence, the 3D MUltiple SIgnal Classification Back Projection (MUSIC BP) with P and pP phases is applied. The combined P- and pP-wave BP imaging of the mainshock shows two stages of anti-parallel ruptures along two depths separating for about 10~15 km. Unusual super-shear ruptures are observed through the 3D BP images of two Mw 6.7 aftershocks. In last two chapters, the 3D BP imaging reveals similar rupture properties of two shallow catastrophic earthquakes (Mw=6.4) in southwestern Taiwan. Both the 2010 Jiashian and 2016 Meinong earthquakes ruptured westward with similar velocity of ~2.5 km/s along a NE-ward shallow dipping blind fault. The rupture similarities of the doublet suggest two parallel elongate asperities along the causative fault. After several decades of seismic quiescence, the 2010 Jiashian event initiated the rupture at the deeper asperity and triggered the shallower asperity which caused catastrophes six years later.
Download or read book A Method for Dynamic Earthquake Rupture Simulation with Applications to a Large Southern San Andreas Scenario written by Geoffrey Palarz Ely and published by . This book was released on 2008 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt: Given the scarcity of near-source recordings for large earthquakes, numerical simulations play an important roll in the prediction of possible ground motion from future events. Simulations also give insight to physical processes of fault rupture that are difficult or impossible to empirically measure. In this dissertation I develop a numerical method to simulate spontaneous shear crack propagation within a heterogeneous, three-dimensional, viscoelastic medium. The implementation is highly scalable, enabling large scale, multi-processor calculations. Wave motions are computed on a logically rectangular hexahedral mesh, using the generalized finite difference method of Support Operators. This approach enables the modeling on nonplanar boundaries, as well as nonplanar ruptures. Computations are second-order in space and time. Stiffness and viscous hourglass corrections are employed to suppress suppress zero-energy grid oscillation modes. Model boundaries may be reflective or absorbing, where absorbing boundaries are handled using the method of perfectly matched layers (PML). Three well known test problems are used to verify various aspects of the numerical method: wave propagation in a layered medium; surface amplification due to a semi-cylindrical canyon; and spontaneous rupture of a rectangular fault. Tests are repeated with varying amounts of simple shear deformation of the mesh. Sufficient accuracy is preserved under high-angle mesh shearing to permit modeling of thrust-earthquake geometries. The method is used to simulate a large (M[omega]7.6) earthquake scenarios along the southern San Andreas fault, using a piecewise planar fault representation and true topography of the ground surface. The crustal velocity structure is taken from the Southern California Earthquake Center Community Velocity Model (SCEC-CVM), which is currently the most complete three-dimensional model available for the region. Heterogeneous initial traction conditions are derived from an inversion of the M7.3 1992 Landers strong ground motion records. Heterogeneity in the traction model leads to focusing of the rupture front, in many cases producing super-shear rupture velocity in areas of high initial traction (asperities). Focusing sometimes occurs between the asperities, with the notable result that highest peak slip rates occur in areas of low initial traction. The overall distribution of simulated peak ground velocities is consistent with those derived from the current empirical models, with some important deviations associated with basin wave-guide and directivity effects.
Download or read book Applied Mechanics Reviews written by and published by . This book was released on 1993 with total page 528 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mathematics of Multidimensional Seismic Imaging Migration and Inversion written by N. Bleistein and published by Springer Science & Business Media. This book was released on 2000-12-15 with total page 546 pages. Available in PDF, EPUB and Kindle. Book excerpt: For more than 80 years, the oil and gas industry has used seismic methods to construct images and determine physical characteristics of rocks that can yield information about oil and gas bearing structures in the earth. This book presents the different seismic data processing methods, also known as seismic "migration," in a unified mathematical way. The book serves as a bridge between the applied math and geophysics communities by presenting geophysicists with a practical introduction to advanced engineering mathematics, while presenting mathematicians with a window into the world of the mathematically sophisticated geophysicist.
Download or read book Geophysics and Geosequestration written by Thomas L. Davis and published by Cambridge University Press. This book was released on 2019-05-09 with total page 391 pages. Available in PDF, EPUB and Kindle. Book excerpt: An overview of the geophysical techniques and analysis methods for monitoring subsurface carbon dioxide storage for researchers and industry practitioners.
Download or read book Planning Land 3 D Seismic Surveys written by Andreas Cordsen and published by SEG Books. This book was released on 2000 with total page 216 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Curvelets written by Emmanuel Jean Candes and published by . This book was released on 1999 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: It is widely believed that to efficiently represent an otherwise smooth object with discontinuities along edges, one must use an adaptive representation that in some sense 'tracks' the shape of the discontinuity set. This folk-belief - some would say folk-theorem - is incorrect. At the very least, the possible quantitative advantage of such adaptation is vastly smaller than commonly believed. We have recently constructed a tight frame of curvelets which provides stable, efficient, and near-optimal representation of otherwise smooth objects having discontinuities along smooth curves. By applying naive thresholding to the curvelet transform of such an object, one can form m-term approximations with rate of L(sup 2) approximation rivaling the rate obtainable by complex adaptive schemes which attempt to track' the discontinuity set. In this article we explain the basic issues of efficient m-term approximation, the construction of efficient adaptive representation, the construction of the curvelet frame, and a crude analysis of the performance of curvelet schemes.
Download or read book Seismic Surface Waves in a Laterally Inhomogeneous Earth written by V.I. Keilis-Borok and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surface waves form the longest and strongest portion of a seismic record excited by explosions and shallow earthquakes. Traversing areas with diverse geologic structures, they 'absorb' information on the properties of these areas which is best retlected in dispersion, the dependence of velocity on frequency. The other prop erties of these waves - polarization, frequency content, attenuation, azimuthal variation of the amplitude and phase - arc also controlled by the medium between the source and the recording station; some of these are affected by the properties of the source itself and by the conditions around it. In recent years surface wave seismology has become an indispensable part of seismological practice. The maximum amplitude in the surface wave train of virtually every earthquake or major explosion is being measured and used by all national and international seismological surveys in the determination of the most important energy parameter of a seismic source, namely, the magnitude M,. The relationship between M, and the body wave magnitude fI1t, is routinely employed in identification of underground nuclear explosions. Surface waves of hundreds of earthquakes recorded every year are being analysed to estimate the seismic moment tensor of earthquake sources, to determine the periods of free oscillations of the Earth, to construct regional dispersion curves from which in turn the crustal and upper mantle structure in various areas is derived, and to evaluate the dissipative parameters of the mantle material.
