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 AutoBATS and 3D MUSIC New Approaches to Imaging Earthquake Rupture Behaviors written by Pei-Ru Jian and published by Springer Nature. This book was released on 2021-09-27 with total page 110 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 Dissertation Abstracts International written by and published by . This book was released on 2008 with total page 800 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 Fault Zone Properties and Earthquake Rupture Dynamics written by Eiichi Fukuyama and published by Academic Press. This book was released on 2009-04-24 with total page 333 pages. Available in PDF, EPUB and Kindle. Book excerpt: The dynamics of the earthquake rupture process are closely related to fault zone properties which the authors have intensively investigated by various observations in the field as well as by laboratory experiments. These include geological investigation of the active and fossil faults, physical and chemical features obtained by the laboratory experiments, as well as the seismological estimation from seismic waveforms. Earthquake dynamic rupture can now be modeled using numerical simulations on the basis of field and laboratory observations, which should be very useful for understanding earthquake rupture dynamics. Features: * First overview of new and improved techniques in the study of earthquake faulting * Broad coverage * Full color Benefits: * A must-have for all geophysicists who work on earthquake dynamics * Single resource for all aspects of earthquake dynamics (from lab measurements to seismological observations to numerical modelling) * Bridges the disciplines of seismology, structural geology and rock mechanics * Helps readers to understand and interpret graphs and maps Also has potential use as a supplementary resource for upper division and graduate geophysics courses.

Download or read book Stress Drop Variability Implications for Earthquake Rupture Processes Scaling Relations and Sesimic Ground Motions written by Aglaja Blanke and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Microscopic and Macroscopic Simulation Towards Predictive Modelling of the Earthquake Process written by Peter Mora and published by Birkhäuser. This book was released on 2013-11-11 with total page 567 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Stress Drop Variability Implications for Earthquake Rupture Processes Scaling Relations and Seismic Ground Motions written by Aglaja Blanke and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Imaging Modeling and Assimilation in Seismology written by Yong-Gang Li and published by Walter de Gruyter. This book was released on 2012-02-22 with total page 273 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.

Download or read book Precise Earthquake Source Parameter Estimation written by Annemarie Susan Baltay and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The question of whether earthquakes, as they increase in size, radiate seismic waves more efficiently is at the core of our understanding of the physics of faulting, as well as our ability to mitigate the effects of strong ground motion. If earthquakes have some intrinsic time or length scale that could be observed or modeled, then seismologists could determine the ultimate size of an earthquake just as it begins to rupture. On the other hand, if earthquakes are self-similar, with no intrinsic time or length scale, than any information learned about the plethora of small and intermediate earthquakes can simply be scaled up to predict parameters, such as ground motion, for larger, more devastating earthquakes. Many studies find that apparent stress and stress drop increase with seismic moment, yet others find an independence of these parameters with moment, obeying self-similar earthquake source physics. Source measurements are controversial due to the inherent difficulty in correcting the radiated waves to negate path and site effects, such as attenuation, scattering or amplification. Independent studies of the same earthquake may find seismic energies that differ by an order of magnitude. Methods to estimate source parameters need to account for these effects, or quantify the range of validity for estimates made with uncorrected seismic records. In this work, I precisely estimate the source parameters radiated seismic energy, apparent stress and stress drop, using both relative spectral measures from empirical Green's functions, and close distance acceleration records. Using relative empirical Green's functions, I can handily negate source and path effects, without explicit consideration of anelastic attenuation. Working with data from 8 sequences of earthquakes in the western US and Honshu, Japan, ranging from M 1.8 to Mw 7.1, I find no clear trend of a dependence of apparent stress or stress drop with moment, finding a constant scaled energy, ER/Mo of 3.5x10-5, or apparent stress of ~ 1 MPa, to fit the data well. The average Brune stress drop for these data is ~5 MPa. By using many stations and relative measures, I statistically show self-similar earthquake scaling. However, there are anomalous enervated and energetic events that show individual departure from the overall trend, representing the true variability in earthquake source parameters. I revisit the aRMS stress drop using recent broadband stations and strong motion accelerometers. The aRMS stress drop samples an inherently different portion of the earthquake spectrum than the Brune stress drop, and can be directly related to PGA and hence high-frequency ground motion. While the aRMS stress drop is much simpler and faster to measure, it does not model attenuation, and hence suffers from loss of signal at distances> ~20 km. At close stations, and for large earthquakes, the aRMS stress drop values are very similar to those of the Brune stress drop, yet with reduced error base on corner frequency uncertainty. That the aRMS[not] method yields stable stress drops supports the assumptions behind the formulation: that earthquake acceleration records can be considered random, band-limited, white Gaussian noise, and overall, a self-similar earthquake model. The last portion of this work focuses on five great earthquakes, Mw> 8.5, over the past 7 years. Because they are so rare, seismologists don't have much information about these devastating events. Understanding how they relate to smaller earthquakes will aid in hazard mitigation. I estimate the radiated seismic energy and apparent stress, using a novel, teleseismic empirical Green's function deconvolution. At near distances, great earthquake are too big to model, as effects from one end of the rupture will interfere with those from other parts, and local recordings are often saturated. But at far distances, ~3000 km -- 9000 km, I show that moderate earthquakes, Mw 6.5 -- 7.5 can be used as Green's functions, and are used to correct the mainshocks from path and site effects. Use of several different eGf earthquakes demonstrates the limitations on the method, but also increases the precision of the energy estimates. I find that both P and S waves give consistent energy estimates when using eGf events. Azimuthal dependence of radiated energy indicates expected rupture directivity, and can be modeled using Haskell line sources to understand the rupture process.

Download or read book Origin Evolution Environmental Impact of Oceanic LIPs written by Clive R. Neal and published by Geological Society of America. This book was released on 2015-05 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: The origin, evolution, and environmental impact of large igneous provinces (LIPs) represents a topic of high scientific importance because the magmatism associated with these features cannot be directly related to plate tectonics, and because the eruption of flood basalts may have global environmental consequences. Oceanic LIPs are even more poorly understood due to their relative inaccessibility. This volume takes a multidisciplinary approach to understanding LIP origin, evolution, and environmental impact in ocean basins. Papers that focus on plate tectonic reconstructions, petrologic and geophysical investigations of various LIPs, and sedimentological and micropaleontological evidence of syn-LIP sediments are presented. Precious materials and data from dredging cruises and scientific ocean drilling expeditions have made this volume possible.

Download or read book Stress Drop and Its Uncertainty for Earthquakes M3 8 5 5 in Central California and Oklahoma written by Luyuan Ding and published by . This book was released on 2015 with total page 51 pages. Available in PDF, EPUB and Kindle. Book excerpt: Stress drop is the stress that is effectively available to drive fault motion. It is a key parameter in predicting peak ground acceleration (PGA), since PGA∝, and it is very important in estimating ground motion. However, it is difficult to get an accurate estimation of stress drop. In order to get a more stable measurement of stress drop, we test two methods in this thesis: the first one is the Brune stress drop, which is more commonly applied, and the second one is the Arms stress drop, which less applied before and theoretically should have less uncertainty. By comparing these two methods we would like to test the feasibility and stability of the Arms method. We applied these two methods to data of earthquakes M3-5.5 in California and Oklahoma. We found that, taking Oklahoma results as an example, the mean value of Brune stress drop is 0.38 MPa, with a multiplicative uncertainty of 3.12, and the mean value of Arms stress drop is 1.04, with a multiplicative uncertainty of 1.79. Therefore we concluded that the Arms method is a good estimator of stress drop, with a smaller uncertainty. We determine the path attenuation so that we can increase the source-station distance of events studied to be as much as 76 km. The path seismic attenuation is a critical parameter that must be included in the analysis.

Download or read book Using Multi scale Dynamic Rupture Models to Improve Ground Motion Estimates written by and published by . This book was released on 2013 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: This project uses dynamic rupture simulations to investigate high-frequency seismic energy generation. The relevant phenomena (frictional breakdown, shear heating, effective normal-stress fluctuations, material damage, etc.) controlling rupture are strongly interacting and span many orders of magnitude in spatial scale, requiring highresolution simulations that couple disparate physical processes (e.g., elastodynamics, thermal weakening, pore-fluid transport, and heat conduction). Compounding the computational challenge, we know that natural faults are not planar, but instead have roughness that can be approximated by power laws potentially leading to large, multiscale fluctuations in normal stress. The capacity to perform 3D rupture simulations that couple these processes will provide guidance for constructing appropriate source models for high-frequency ground motion simulations. The improved rupture models from our multi-scale dynamic rupture simulations will be used to conduct physicsbased (3D waveform modeling-based) probabilistic seismic hazard analysis (PSHA) for California. These calculation will provide numerous important seismic hazard results, including a state-wide extended earthquake rupture forecast with rupture variations for all significant events, a synthetic seismogram catalog for thousands of scenario events and more than 5000 physics-based seismic hazard curves for California.

Download or read book Improving Earthquake Source Spectrum Estimation Using Multitaper Techniques written by German A. Prieto and published by . This book was released on 2007 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt: Given that in the methods discussed above the seismic parameters were estimated from the spectrum of the seismic waves, we present a new multitaper algorithm that has significant bias reduction compared to standard multitaper techniques and at the same time reducing the roughness of the estimated spectrum. We show that the method has the ability to estimate both the spectrum and its slope, thus increasing the degrees of freedom if parameters are to be estimated.

Download or read book Theory of Earthquake Premonitory and Fracture Processes written by Roman Teisseyre and published by . This book was released on 1995 with total page 676 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Imaging Earthquake Rupture by Waveform Inversion written by Brian P. Cohee and published by . This book was released on 1995 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Quantifying Uncertainty in Earthquake Rupture Models written by Morgan T. Page and published by ProQuest. This book was released on 2007 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt: Using dynamic and kinematic models, we analyze the ability of GPS and strong-motion data to recover the rupture history of earthquakes. By analyzing the near-source ground-motion generated by earthquake ruptures through barriers and asperities, we determine that both the prestress and yield stress of a frictional inhomogeneity can be recovered. In addition, we find that models with constraints on rupture velocity have less ground motion than constraint-free, spontaneous dynamic models with equivalent stress drops. This suggests that kinematic models with such constraints overestimate the actual stress heterogeneity of earthquakes.