Crustal Deformation Associated With Great Subduction Earthquakes PDF Download
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| Author | : Tianhaozhe Sun |
| Publisher | : |
| Total Pages | : |
| Release | : 2017 |
| Genre | : |
| ISBN | : |
Download Crustal Deformation Associated with Great Subduction Earthquakes Book in PDF, ePub and Kindle
The slip behaviour of subduction faults and the viscoelastic rheology of Earth's mantle govern crustal deformation throughout the subduction earthquake cycle. This Ph.D. dissertation presents research results on two topics: (1) coseismic and postseismic slip of the shallowest segment of subduction faults and (2) postseismic deformation following great subduction earthquakes controlled by mantle viscoelasticity. Topic 1: Slip behaviour of the shallowest subduction faults. By modelling high-resolution cross-trench bathymetry surveys before and after the 2011 Mw 9.0 Tohoku-oki earthquake, we determine the magnitude and distribution of coseismic slip over the most near-trench 40 km of the Japan Trench megathrust. The inferred > 60 m average slip and a gentle increase by 5 m towards the trench over this distance indicate moderate degree of net coseismic weakening of the shallow fault. Using near-trench seafloor and sub-seafloor fluid pressure variations as strain indicators in conjunction with land-based geodetic measurements, we determine coseismic-slip and afterslip distributions of the 2012 Mw 7.6 Costa Rica earthquake. Here, trench-breaching slip similar to the Tohoku-oki rupture did not occur during the earthquake, but afterslip extended to the trench axis and reached ~0.7 m over 1.3 years after the earthquake, exhibiting a velocity-strengthening behaviour. These two contrasting examples bracket a possibly wide range of slip behaviour of the shallow megathrust. They help us understand why large tsunamis are generated by some but not all subduction earthquakes. Topic 2: Postseismic deformation following great subduction earthquakes. Due to the asymmetry of megathrust rupture, with the upper plate undergoing greater coseismic tension than the incoming plate, viscoelastic stress relaxation causes the trench and land areas to move in opposite, opposing directions immediately after the earthquake. Seafloor geodetic measurements following the 2011 Tohoku-oki earthquake, modelled in this work, provided the first direct observational evidence for this effect. Systematic modelling studies in this work suggest that such viscoelastic opposing motion should be common to all Mw ≥ 8 subduction earthquakes. As the effect of viscoelastic relaxation decays with time and the effect of fault relocking becomes increasingly dominant, the dividing boundary of the opposing motion continues to migrate away from the rupture area. Comparative studies of ten 8 ≤ Mw ≤ 9.5 subduction earthquakes in this dissertation quantifies the primary role of earthquake size in controlling the "speed" of the evolution of this deformation. Larger earthquakes are followed by longer-lived opposing motion that affects a broader region of the upper plate.
| Author | : Yan Hu |
| Publisher | : |
| Total Pages | : |
| Release | : 2011 |
| Genre | : |
| ISBN | : |
Download Deformation Processes in Great Subduction Zone Earthquake Cycles Book in PDF, ePub and Kindle
This dissertation consists of two parts and investigates the crustal deformation associated with great subduction zone earthquake at two different spatial scales. At the small scale, I investigate the stress transfer along the megathrust during great earthquakes and its effects on the forearc wedge. At the large scale, I investigate the viscoelastic crustal deformation of the forearc and the back arc associated with great earthquakes. Part I: In a subduction zone, the frontal region of the forearc can be morphologically divided into the outer wedge and the inner wedge. The outer wedge which features much active plastic deformation has a surface slope angle generally larger than that of the inner wedge which hosts stable geological formations. The megathrust can be represented by a three-segment model, the updip zone (velocity-strengthening), seismogenic zone (velocity-weakening), and downdip zone (velocity-strengthening). Our dynamic Coulomb wedge theory postulates that the outer wedge overlies the updip zone, and the inner wedge overlies the seismogenic zone. During an earthquake, strengthening of the updip zone may result in compressive failure in the outer wedge. The inner wedge undergoes elastic deformation. I have examined the geometry and mechanical processes of outer wedges of twenty-three subduction zones. The surface slope of these wedges is generally too high to be explained by the classical critical taper theory but can be explained by the dynamic Coulomb wedge theory. Part II: A giant earthquake produces coseismic seaward motion of the upper plate and induces shear stresses in the upper mantle. After the earthquake, the fault is re-locked, causing the upper plate to move slowly landward. However, parts of the fault will undergo continuous aseismic afterslip for a short duration, causing areas surrounding the rupture zone to move seaward. At the same time, the viscoelastic relaxation of the earthquake-induced stresses in the upper mantle causes prolonged seaward motion of areas farther landward including the forearc and the back arc. The postseismic and interseismic crustal deformation depends on the interplay of these three primary processes. I have used three-dimensional viscoelastic finite element models to study the contemporary crustal deformation of three margins, Sumatra, Chile, and Cascadia, that are presently at different stages of their great earthquake cycles. Model results indicate that the earthquake cycle deformation of different margins is governed by a common physical process. The afterslip of the fault must be at work immediately after the earthquake. The model of the 2004 Sumatra earthquake constrains the characteristic time of the afterslip to be 1.25 yr. With the incorporation of the transient rheology, the model well explains the near-field and far-field postseismic deformation within a few years after the 2004 Sumatra event. The steady-state viscosity of the continental upper mantle is determined to be 10^19 Pa S, two orders of magnitude smaller than that of the global value obtained through global postglacial rebound models.
| Author | : Haipeng Luo |
| Publisher | : |
| Total Pages | : |
| Release | : 2021 |
| Genre | : |
| ISBN | : |
Download Understanding Subduction-zone Rheology and Crustal Deformation in Earthquake Cycles Book in PDF, ePub and Kindle
My PhD program is focused on how earthquake cycle deformation in subduction zones is governed by the rheology of the asthenosphere and lithosphere. The method of research is numerical modelling of deformation processes constrained by geodetic observations. This dissertation includes research results on the three deformation phases of earthquake cycles, namely the coseismic, postseismic, and interseismic phases. Coseismic: Tension cracks were produced by megathrust earthquakes in the Chile-Peru forearc, seemingly challenging the elastic rebound theory. We explain the cracks as the consequence of less or no interseismic stress accumulation in the near-surface material due to its viscoelastic behaviour, in contrast to the deeper elastic crust. Elastic rebound of the deeper crust during earthquakes induces more stress in the near-surface material than has been accumulated and thus generates the tensile failure. The results confirm the validity of the elastic rebound theory and highlight the importance of understanding the heterogeneity of lithosphere rheology. Postseismic: A sharp contrast between the cold forearc and hot arc and backarc, considered fundamental to subduction dynamics, indicates the presence of a cold mantle wedge nose, but direct evidence is limited. The cold nose, if present, should behave elastically for the time scale of earthquake cycles. Through modelling postseismic vertical motion following great subduction earthquakes, we propose and demonstrate that global observations of postseismic uplift just seaward of the volcanic arc provide a geodetic signature of the cold nose. This finding helps to establish a link between the relatively short-term earthquake cycle deformation with long-term thermo-petrologic processes. It also solves a mystery that has puzzled the scientific community for six decades regarding crustal deformation caused by the largest recorded earthquake on Earth - the1960 moment magnitude (Mw) 9.5 Chile earthquake. Interseismic: In the southern area of the 1960 Mw 9.5 Chile earthquake, regional geodetic measurements in the 21st century show a rapid systematic landward increase in the velocity of station motion that cannot be explained by the standard viscoelastic earthquake cycle model. We propose that the velocity increase is due to a sudden downdip widening of the zone of megathrust locking. This finding not only raises new theoretical questions for the study of megathrust fault mechanics but also has important implications to assessing seismic hazard in the subduction zone environment. In addition to the earthquake cycle deformation studies, we explore along-strike viscosity variations in a slab window associated with the Chile triple junction which terminated the southward rupture propagation of the 1960 Chile earthquake. We model geodetically observed ongoing surface uplift due to recent climatically induced mass loss at the Patagonian icefields that are situated just above the slab window. The results suggest an order of magnitude viscosity contrast within the slab window, with the younger and thus warmer northern part being much less viscous. This case study provides an example for how the anatomy of an active tectonic system can be geodetically "imaged" using non-tectonic signals.
| Author | : Mitsuhiro Matsu'ura |
| Publisher | : Birkhäuser |
| Total Pages | : 360 |
| Release | : 2012-12-06 |
| Genre | : Science |
| ISBN | : 3034881975 |
Download Earthquake Processes: Physical Modelling, Numerical Simulation and Data Analysis Part II Book in PDF, ePub and Kindle
In the last decade of the 20th century, there has been great progress in the physics of earthquake generation; that is, the introduction of laboratory-based fault constitutive laws as a basic equation governing earthquake rupture, quantitative description of tectonic loading driven by plate motion, and a microscopic approach to study fault zone processes. The fault constitutive law plays the role of an interface between microscopic processes in fault zones and macroscopic processes of a fault system, and the plate motion connects diverse crustal activities with mantle dynamics. An ambitious challenge for us is to develop realistic computer simulation models for the complete earthquake process on the basis of microphysics in fault zones and macro-dynamics in the crust-mantle system. Recent advances in high performance computer technology and numerical simulation methodology are bringing this vision within reach. The book consists of two parts and presents a cross-section of cutting-edge research in the field of computational earthquake physics. Part I includes works on microphysics of rupture and fault constitutive laws, and dynamic rupture, wave propagation and strong ground motion. Part II covers earthquake cycles, crustal deformation, plate dynamics, and seismicity change and its physical interpretation. Topics in Part II range from the 3-D simulations of earthquake generation cycles and interseismic crustal deformation associated with plate subduction to the development of new methods for analyzing geophysical and geodetical data and new simulation algorithms for large amplitude folding and mantle convection with viscoelastic/brittle lithosphere, as well as a theoretical study of accelerated seismic release on heterogeneous faults, simulation of long-range automaton models of earthquakes, and various approaches to earthquake predicition based on underlying physical and/or statistical models for seismicity change.
| Author | : Joseph Alan Henton |
| Publisher | : |
| Total Pages | : |
| Release | : 2000 |
| Genre | : |
| ISBN | : |
Download GPS Studies of Crustal Deformation in the Northern Cascadia Subduction Zone Book in PDF, ePub and Kindle
Vancouver Island, located in southwestern coastal British Columbia, overlies the northern portion of the Cascadia Subduction Zone. This region is characterized by extensive seismicity which includes M ∼ 7 crustal earthquakes and less frequent M ∼ 9 megathrust events. Crustal deformation measurements have been carried out in this region since 1978 using various geodetic field techniques: levelling, tide gauge studies, precise gravity, laser ranging, and most recently, GPS. Earlier survey data provided key constraints to elastic slip-dislocation models for estimating the size and location of the rupture area for the next subduction-thrust earthquake. Recent estimates of crustal motions within the North Cascadia Margin based on both campaign GPS network surveys and up to 6.5 years of data from continuous GPS sites are consistent with the strain accumulation expected from a locked subduction fault. The deformation vectors are in the direction of plate convergence within the uncertainty of plate motion models. The observed strain rate across Vancouver Island is, however, smaller (by approximately a factor of 1.5) than the dislocation model prediction, suggesting the presence of visco-elastic effects. Crustal deformation measurements for central Vancouver Island fail to resolve motions that could be associated with the occurrence of large crustal earthquakes, and also suggest that the extent of the seismogenic subduction thrust zone north of the Nootka Fault Zone is extremely limited.
| Author | : Timothy H. Dixon |
| Publisher | : Columbia University Press |
| Total Pages | : 696 |
| Release | : 2007 |
| Genre | : Computers |
| ISBN | : 9780231138666 |
Download The Seismogenic Zone of Subduction Thrust Faults Book in PDF, ePub and Kindle
Subduction zones, one of the three types of plate boundaries, return Earth's surface to its deep interior. Because subduction zones are gently inclined at shallow depths and depress Earth's temperature gradient, they have the largest seismogenic area of any plate boundary. Consequently, subduction zones generate Earth's largest earthquakes and most destructive tsunamis. As tragically demonstrated by the Sumatra earthquake and tsunami of December 2004, these events often impact densely populated coastal areas and cause large numbers of fatalities. While scientists have a general understanding of the seismogenic zone, many critical details remain obscure. This volume attempts to answer such fundamental concerns as why some interplate subduction earthquakes are relatively modest in rupture length (greater than 100 km) while others, such as the great (M greater than 9) 1960 Chile, 1964 Alaska, and 2004 Sumatra events, rupture along 1000 km or more. Contributors also address why certain subduction zones are fully locked, accumulating elastic strain at essentially the full plate convergence rate, while others appear to be only partially coupled or even freely slipping; whether these locking patterns persist through the seismic cycle; and what is the role of sediments and fluids on the incoming plate. Nineteen papers written by experts in a variety of fields review the most current lab, field, and theoretical research on the origins and mechanics of subduction zone earthquakes and suggest further areas of exploration. They consider the composition of incoming plates, laboratory studies concerning sediment evolution during subduction and fault frictional properties, seismic and geodetic studies, and regional scale deformation. The forces behind subduction zone earthquakes are of increasing environmental and societal importance.
| Author | : Chelsea Phipps Scott |
| Publisher | : |
| Total Pages | : 392 |
| Release | : 2017 |
| Genre | : |
| ISBN | : |
Download Coseismic Deformation Observed with Radar Interferometry Book in PDF, ePub and Kindle
Spatially dense maps of coseismic deformation derived from Interferometric Synthetic Aperture Radar (InSAR) datasets result in valuable constraints on earthquake processes. The recent increase in the quantity of observations of coseismic deformation facilitates the examination of signals in many tectonic environments associated with earthquakes of varying magnitude. Efforts to place robust constraints on the evolution of the crustal stress field following great earthquakes often rely on knowledge of the earthquake location, the fault geometry, and the distribution of slip along the fault plane. Well-characterized uncertainties and biases strengthen the quality of inferred earthquake source parameters, particularly when the associated ground displacement signals are near the detection limit. Well-preserved geomorphic records of earthquakes offer additional insight into the mechanical behavior of the shallow crust and the kinematics of plate boundary systems. Together, geodetic and geologic observations of crustal deformation offer insight into the processes that drive seismic cycle deformation over a range of timescales. In this thesis, I examine several challenges associated with the inversion of earthquake source parameters from SAR data. Variations in atmospheric humidity, temperature, and pressure at the timing of SAR acquisitions result in spatially correlated phase delays that are challenging to distinguish from signals of real ground deformation. I characterize the impact of atmospheric noise on inferred earthquake source parameters following elevation-dependent atmospheric corrections. I analyze the spatial and temporal variations in the statistics of atmospheric noise from both reanalysis weather models and InSAR data itself. Using statistics that reflect the spatial heterogeneity of atmospheric characteristics, I examine parameter errors for several synthetic cases of fault slip on a basin-bounding normal fault. I show a decrease in uncertainty in fault geometry and kinematics following the application of atmospheric corrections to an event spanned by real InSAR data, the 1992 M5.6 Little Skull Mountain, Nevada, earthquake. Finally, I discuss how the derived workflow could be applied to other tectonic problems, such as solving for interseismic strain accumulation rates in a subduction zone environment. I also study the evolution of the crustal stress field in the South American plate following two recent great earthquakes along the Nazca- South America subduction zone. I show that the 2010 Mw 8.8 Maule, Chile, earthquake very likely triggered several moderate magnitude earthquakes in the Andean volcanic arc and backarc. This suggests that great earthquakes modulate the crustal stress field outside of the immediate aftershock zone and that far-field faults may pose a heightened hazard following large subduction earthquakes. The 2014 Mw 8.1 Pisagua, Chile, earthquake reopened ancient surface cracks that have been preserved in the hyperarid forearc setting of northern Chile for thousands of earthquake cycles. The orientation of cracks reopened in this event reflects the static and likely dynamic stresses generated by the recent earthquake. Coseismic cracks serve as a reliable marker of permanent earthquake deformation and plate bo...
| Author | : Steffi Burchardt |
| Publisher | : Elsevier |
| Total Pages | : 356 |
| Release | : 2018-05-09 |
| Genre | : Science |
| ISBN | : 0128097507 |
Download Volcanic and Igneous Plumbing Systems Book in PDF, ePub and Kindle
Volcanic and Igneous Plumbing Systems: Understanding Magma Transport, Storage, and Evolution in the Earth's Crust synthesizes research from various geoscience disciplines to examine volcanic and igneous plumbing systems (VIPS) in-depth. VIPS comprise a network of magma transport and storage features in the Earth’s crust. These features include dykes, sills and larger magma bodies that form the pathway and supply system of magma beneath active volcanoes. Combining basic principles with world-class research and informative illustrations, this unique reference presents a holistic view of each topic covered, including magma transport, magma chambers, tectonics and volcanism. Addressing a variety of approaches to these topics, this book offers researchers and academics in the Earth Science fields, such as geophysics, volcanology and igneous petrology the information they need to apply the information to their own disciplines. Provides an easily understandable overview of current research on volcanic and igneous plumbing systems Includes full color illustrations to increase understanding Covers fundamental information needed to optimize comprehension Features a field example from world-class research in each chapter, including photographs and maps
| Author | : Robert S. Yeats |
| Publisher | : |
| Total Pages | : 70 |
| Release | : 1967 |
| Genre | : Geology |
| ISBN | : |
Download Field Trip to Pliocene in the Ventura Basin Book in PDF, ePub and Kindle
| Author | : Serge Lallemand |
| Publisher | : Springer Science & Business Media |
| Total Pages | : 278 |
| Release | : 2009-02-11 |
| Genre | : Science |
| ISBN | : 3540879749 |
Download Subduction Zone Geodynamics Book in PDF, ePub and Kindle
Subduction is a major process that plays a first-order role in the dynamics of the Earth. The sinking of cold lithosphere into the mantle is thought by many authors to be the most important source of energy for plates driving forces. It also deeply modifies the thermal and chemical structure of the mantle, producing arc volcanism and is responsible for the release of most of the seismic energy on Earth. There has been considerable achievements done during the past decades regarding the complex interactions between the various processes acting in subduction zones. This volume contains a collection of contributions that were presented in June 2007 in Montpellier (France) during a conference that gave a state of the art panorama and discussed the perspectives about "Subduction Zone Geodynamics". The papers included in this special volume offer a unique multidisciplinary picture of the recent research on subduction zones geodynamics. They are organized into five main topics: Subduction zone geodynamics, Seismic tomography and anisotropy, Great subduction zone earthquakes, Seismogenic zone characterization, Continental and ridge subduction processes. Each of the 13 papers collected in the present volume is primarily concerned with one of these topics. However, it is important to highlight that papers always treat more than one topic so that all are related lighting on different aspects of the complex and fascinating subduction zones geodynamics.
