Download Free Earthquake Nucleation On Geometrically Complex Faults Book in PDF and EPUB Free Download. You can read online Earthquake Nucleation On Geometrically Complex Faults and write the review.

We have employed numerical approaches to study earthquake nucleation on geometrically complex faults governed by either slip-dependent friction or rate- and state-dependent friction. The interactions of fault friction, complex fault geometry and remote slow stressing from plate tectonics are investigated. In particular, we focus on characterizing three important physical aspects of an earthquake: the occurrence time, hypocenter location and earthquake source dimensions. Using a slip dependent friction law, we have investigated earthquake nucleation on both thrust and normal dip-slip faults with changes in dip (bends) at depth. Our results show that earthquakes tend to nucleate at shallower depth on thrust faults as compared to those on normal faults with the same geometry. Nucleation time increases significantly as the fault plane are bent more severe for both thrust and normal faults. Using the rate- and state-dependent friction, we studied nucleation on two parallel planar faults with step-over features. We focus on investigating how nucleation is affected by the offset between the two faults. We found that for faults with compressional step-overs, earthquakes tend to nucleate the end of the overlapping zone when the offset is small, but generally nucleate further away from the overlapping end as the offset becomes larger. For faults with extensional step-overs, nucleation always occurs near the overlapping end for all the offsets considered. Our studies provide better understanding of the effects of fault geometry on earthquake nucleation and form a basis for the study of nucleation on large scale geometrically complex fault systems such as fault systems in Southern California. Our results may also provide realistic earthquake source conditions for rupture dynamics studies which at present largely employ ad hoc source conditions.
The destructive force of earthquakes has stimulated human inquiry since ancient times, yet the scientific study of earthquakes is a surprisingly recent endeavor. Instrumental recordings of earthquakes were not made until the second half of the 19th century, and the primary mechanism for generating seismic waves was not identified until the beginning of the 20th century. From this recent start, a range of laboratory, field, and theoretical investigations have developed into a vigorous new discipline: the science of earthquakes. As a basic science, it provides a comprehensive understanding of earthquake behavior and related phenomena in the Earth and other terrestrial planets. As an applied science, it provides a knowledge base of great practical value for a global society whose infrastructure is built on the Earth's active crust. This book describes the growth and origins of earthquake science and identifies research and data collection efforts that will strengthen the scientific and social contributions of this exciting new discipline.
The geometry of faults and fault systems affects the source mechanics of earthquakes and the deformation associated with slip on faults. This dissertation investigates aspects of the geometry of fault surfaces, in particular those with non-planar topology. I quantify the surface geometry using the tools of differential geometry to evaluate the geometry in a spatially coherent way. The study finds that at cm-scale ([approximately equal to]2cm) fault surfaces have no clear pattern of basic shapes succession, while at larger scales (10cm-50cm) corrugations along the slip direction are predominant while small undulations parallel to the direction of sliding exist on the cm-scale. The changes in surface shape and orientation lead to changes in resolved traction on the order of a few MPa for crustal settings, which far exceed generally associated triggering stresses. The undulations significantly retard slip on heuristic faults when compared to those lacking undulations. Geometric fault surface complexity on a crustal scale faults is investigated using relocated seismicity from a catalog of events for the Joshua Tree - Landers earthquake sequence. The spatial density of seismicity is used to locate finite width fault zones and construct surfaces indicative of the centers of these fault zones. The method identifies ten separate faults that exhibit significant non-planar geometry. The mechanical effects of the geometrically complex fault surfaces are illustrated using solutions to the quasi-static boundary value problem. I investigate the resultant stresses and tractions induced by slip on the Joshua Tree fault before the rupture of the Landers earthquake. The propensity for slip on the Landers faults is increased in regions of initiation and largest slip during the subsequent event. The geometrically complex models predict greater propensity for slip along the northern faults involved in the Landers earthquake than the commonly used planar and vertical four-fault models. The stresses adjacent to the Joshua Tree fault are investigated by calculating the changes in Coulomb stresses on optimally oriented surfaces of weakness. The geometrically complex model for Joshua Tree fault predicts the aftershocks immediately following the Joshua Tree earthquake quite well, and better than the planar fault model. Stress inversions are a useful and popular tool for structural geologist and seismologist alike. Many studies employ these methods on isolated faults or on fault system with limited ranges of orientations, which can lead to erroneous results. I propose a new method that incorporates the effects of mechanical interaction of the entire fault or fault system, solves the complete mechanical boundary value problem problem rather than employing empirical relationships between slip and stress or strain (faultless inversion). The method is tested on synthetic faults with various orientations to evaluate the effects of non-planarity and I find that the lack of varying normal vector orientations can introduce significant errors even for simple idealized cases. The effect of diversity of fault orientations are tested and the results indicate that faultless inversions do not perform as well for limited ranges of orientations when compared to the proposed method. The 1999 Chi-Chi, Taiwan, earthquake is used to test the proposed method. The resulting stress orientations are in good agreement with results from faultless inversions. Furthermore, slip distribution results are in general agreement with kinematic slip inversions using co-seismic surface deformation. Stress inversion methods using fault slip data can thus be improved upon, significantly in many cases, by solving a mechanical boundary value problem that takes into account the geometry of faults or fault systems.
Accompanying CD-ROM has same title as book.
This edited volume is based on the best papers accepted for presentation during the 1st Springer Conference of the Arabian Journal of Geosciences (CAJG-1), Tunisia 2018. This special volume is of interest to all researchers practicing geosphysicists/seismologists, students of PG and UG in the fields of multifaceted Geoscience. Major applications with relevant illustrations presented in the volume are from Middle East. And therefore, this book no doubt would serve as a reference guide to all geoscientists and students in the broad field of Earth Science. This volume covers significant applications of gravity and magnetic methods, electrical and electromagnetic methods, refraction and reflection seismic methods besides a large number of study on earthquakes, tectonics and geological settings etc. The salient features of this volume are the interpretation and modeling of geophysical data of different nature. Main topics include: 1. Applications of gravity and magnetic methods.2. Electrical and Electromagnetic methods in mineral and groundwater exploration.3. Case studies on refraction and reflection seismic methods.4. Integrated geoscience applications in the exploration of subsurface resources.5. Hydrocarbon and petrophysical studies6. Earthquakes and seismic hazard assessment.7. Tectonics
This special issue of Pure and Applied Geophysics is the second of two volumes containing an augmented collection of papers originating from the Evison Symposium on Seismogenesis and Earthquake Forecasting held in Wellington, New Zealand, in February 2008. The volumes honor Frank Evison's interest in earthquake generation and forecasting. This volume includes descriptions of earthquake forecasting test centers through the Collaboratory for the Study of Earthquake Predictability (CSEP) program and the first results from the Regional Earthquake Likelihood Model (RELM) experiment in California. Other papers discuss methods of testing predictions, in particular by the use of error diagrams. There is discussion of prediction methodologies using seismicity, including an application of the statistical technique of Hidden Markov Models to identify changes in seismicity and a new technique for identifying precursory quiescence. Several papers employ other data besides seismicity, such as geologically determined faults, calculations of stress changes via Coulomb stress modeling, tomographically determined velocity structure, groundwater, crustal deformation, and comparisons of real earthquakes to synthetic seismicity determined from hypothesized earthquake physics. One paper focuses on the prediction of human casualties in the event that a large earthquake occurs anywhere on the globe. The volume will be useful to students and professional researchers who are interested in the earthquake preparation process and in converting that understanding into forecasts of earthquake occurrence.
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 colorBenefits:* 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 mapsAlso has potential use as a supplementary resource for upper division and graduate geophysics courses.