Imaging the Rupture Processes of Earthquakes Using the Relative Back-Projection Method PDF Download
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Author: Hao Zhang
Publisher: Springer
ISBN: 3662552396
Category : Science
Languages : en
Pages : 127
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Book Description
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.
Author: Hao Zhang
Publisher: Springer
ISBN: 3662552396
Category : Science
Languages : en
Pages : 127
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Book Description
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.
Author: Marina Corradini
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
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.
Author: Pei-Ru Jian
Publisher: Springer Nature
ISBN: 9811655847
Category : Science
Languages : en
Pages : 110
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Book Description
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.
Author: Bettina P. Allmann
Publisher: ProQuest
ISBN: 9780549598404
Category :
Languages : en
Pages : 146
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Book Description
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.
Author: Ailin Zhang
Publisher:
ISBN:
Category :
Languages : en
Pages : 174
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Book Description
Earthquake source imaging is an efficient tool to reveal the kinematic rupture process of earthquakes. The accuracy and robustness of source imaging is of vital importance to con- strain source properties and help discriminate among potential physical mechanisms. In this work, I develop array-based approach: enhanced back-projection and coherence method to provide better constraints on kinematic source imaging. Slowness correction is proposed to improve the source imaging of complicated rupture in conjugate fault systems. The correction is capable of mitigating 3D structural effects that commonly exist for M8 earthquakes. For deep earthquakes, I introduce 3D back-projection which provides depth resolution of the rupture front. Resolving ruptures in 3D space helps us to understand the rupture process and physical mechanisms of deep earthquakes. Furthermore, coherence model is established to relate earthquake source size with inter-station cross-correlation. This method creates independent measures to validate and constrain the source sizes of deep earthquakes. Aforementioned array-based approaches have been successfully applied to recently oc- curred earthquakes, and I will take this chance to revisit the rupture mechanisms of the events revealed by enhanced source imaging
Author: Wenyuan Fan
Publisher:
ISBN:
Category :
Languages : en
Pages : 342
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Book Description
Earthquakes are the primary source of seismic waves in seismology and understanding the earthquake source is essential for predicting ground motions and detailing the physics of rupture. Earthquake kinematic source imaging describes the whole rupture process during an earthquake. It does not directly require the resolved source model to be physically or dynamically plausible, but can help in understanding the conditions of rupture dynamics. Therefore, accurate earthquake source models are highly desirable. In Chapter 2, we develop a frequency-based approach to earthquake slip inversion that requires no prior information on the rupture velocity or slip-rate functions. In Chapter 3, we characterize the rupture process of the 25 April 2015 Nepal earthquake with globally recorded teleseismic P waves. In Chapter 4, we investigate the 10 January 2012 Mw 7.2 Sumatra earthquake in the Wharton basin and detect dynamically-triggered large early aftershocks occurring on or near the subduction interface. In Chapter 5, we constrain the spatiotemporal evolution of the 2009 Tonga-Samoa earthquake with global P-wave back-projection and a multiple moment-tensor inversion. Our results show that the rupture branches east of the trench axis were controlled by the geometry of bending-related faults on the Pacific plate, and that the rupture branch west of the trench axis may correlate with along-strike fore-arc segmentation. In Chapter 6, we detect and locate 48 previously unidentified large early aftershocks triggered by 7
Author: Yong-Gang Li
Publisher: Walter de Gruyter
ISBN: 3110259036
Category : Science
Languages : en
Pages : 273
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Book Description
This work presents current approaches in geophysical research of earthquakes. A global authorship from top institutions presents case studies to model, measure, and monitor earthquakes. Among others a full-3D waveform tomography method is introduced, as well as propagator methods for modeling and imaging. In particular the earthquake prediction method makes this book a must-read for researchers in the field.
Author:
Publisher:
ISBN: 9781339160528
Category :
Languages : en
Pages : 404
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Book Description
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.
Author:
Publisher: Elsevier
ISBN: 0444538038
Category : Science
Languages : en
Pages : 5604
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Book Description
Treatise on Geophysics, Second Edition, is a comprehensive and in-depth study of the physics of the Earth beyond what any geophysics text has provided previously. Thoroughly revised and updated, it provides fundamental and state-of-the-art discussion of all aspects of geophysics. A highlight of the second edition is a new volume on Near Surface Geophysics that discusses the role of geophysics in the exploitation and conservation of natural resources and the assessment of degradation of natural systems by pollution. Additional features include new material in the Planets and Moon, Mantle Dynamics, Core Dynamics, Crustal and Lithosphere Dynamics, Evolution of the Earth, and Geodesy volumes. New material is also presented on the uses of Earth gravity measurements. This title is essential for professionals, researchers, professors, and advanced undergraduate and graduate students in the fields of Geophysics and Earth system science. Comprehensive and detailed coverage of all aspects of geophysics Fundamental and state-of-the-art discussions of all research topics Integration of topics into a coherent whole
Author: Eric Daniel Kiser
Publisher:
ISBN:
Category : Earthquakes
Languages : en
Pages : 386
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Book Description
