In this dissertation, I use space-based geodetic data to study the ground deformation caused by the earthquake cycle processes. Chapter 1 is an introduction to the data I used and the motivation on each of the following chapters. Chapter 2 focuses on investigating a controversial problem brought up by several co-seismic inversions using geodetic data, which is called the shallow slip deficit. I explored whether this problem is largely an artifact of inversion due to incomplete data and refined the magnitude of this deficit. Chapter 3, following Chapter 2 develops a new data-driven spectral expansion approach for co-seismic slip inversion using geodetic data. Compared to traditional method, it isolates the unstable part of the model and only solves for the well-determined part. Meanwhile we also developed a 1-D thermal model to understand the different down-dip rupture limits of continental-continental and continental-oceanic megathrust events. Chapter 4 aims at understanding the new TOPS mode data from Sentinel-1 satellites and fully testing the capability of this dataset. A subsidence of about 160 mm/yr at the Cerro Prieto Geothermal Field is recovered together with a 40 mm/yr tectonic fault parallel motion at the nearby region. Chapter 5 further develops the processing algorithm used in Chapter 4 and uses Sentinel-1 data to reveal both tectonic and anthropogenic deformation along the San Andreas Fault System.

The work presented in my dissertation focuses on the crustal deformation during the co- and postseismic periods in earthquake cycles. I use geodetic and seismic data to constrain and better understand the behavior of the earthquake source during the coseismic period. For the postseismic period, I use geodetic data to observe the surface displacements from centimeter-scale to millimeter-scale from an Mw 7.9 and Mw 6.9 event, respectively. I model different mechanisms to explain the postseismic deformation and to further constrain the crustal and upper mantle rheology. For the coseismic earthquake source study, I explore the source of the 2010 Mw 6.3 Jia-Shian, Taiwan earthquake. I develop finite-source models using a combination of seismic data (strong motion and broadband) and geodetic data (InSAR and GPS) to understand the rupture process and slip distribution of this event. The main shock is a thrust event with a small left-lateral component. Both the main shock and aftershocks are located in a transition zone where the depth of seismicity and an inferred regional basal detachment increases from central to southern Taiwan. The depth of this event and the orientation of its compressional axis suggest that this event involves the reactivation of a deep and weak pre-existing NW-SE geological structure. The 1989 Mw 6.9 Loma Prieta earthquake provides the first opportunity since the 1906 San Francisco (Mw 7.9) earthquake to study postseismic relaxation processes and estimate rheological parameters in the region with modern space geodetic tools. The first five years postseismic displacements can be interpreted to be due to aseismic right-oblique fault slip on or near the coseismic rupture, as well as thrusting up-dip of the rupture within the Foothills thrust belt. However, continuing transient surface displacements (d"5 mm/yr) until 2002 revealed by PSInSAR and GPS in the northern Santa Cruz Mountains may indicate a longer-term postseismic deformation. I model the viscoelastic relaxation of the lower crust and upper mantle following the Loma Prieta earthquake to explain the surface displacement. A 14-km-thick lower crust (16 - 30 km depth) viscosity of> 1019 Pa s and an upper mantle viscosity of ~1018 Pa s best explain the geodetic data. The weak upper mantle viscosity in this area is in good agreement with upper mantle rheology in southern California (0.46 - 5 × 1019 Pa s) using a similar approach from studying the postseismic deformation following the 1999 (Mw 7.1) Hector Mine earthquake. Periods of accelerated postseismic deformation following large earthquakes reflect the response of the Earth's lithosphere to sudden coseismic stress changes. I investigate postseismic displacements following the 2008 Wenchuan (Mw 7.9), China earthquake in eastern Tibet and probe the differences in rheological properties across the edge of the Tibetan Plateau. Based on nearly two years of GPS and InSAR measurements, I find that the shallow afterslip on the Beichuan Fault can explain the near-field displacements, and the far-field displacements can be explained by a viscoelastic lower crust beneath Tibet with an initial effective viscosity of 4.4 × 1017 Pa s and a long-term viscosity of 1018 Pa s. On the other hand, the Sichuan Basin block has a high-viscosity upper mantle (> 1020 Pa s) underlying an elastic 35-km-thick crust. The inferred strong contrast in lithospheric rheologies between the Tibetan Plateau and the Sichuan Basin is consistent with models of ductile lower crustal flow that predict maximum topographic gradients across the Plateau margins where viscosity differences are greatest. With additional 6-year-long continuous GPS measurements deployed in the eastern Tibetan Plateau and the Sichuan Basin, viscoelastic relaxation models with the same geometry setups suggests Tibetan lower crust with an initial effective viscosity of 9 × 1017 Pa s and steady-state viscosity of 1019 Pa s. I also use the laboratory experiments derived power law flow model to fit the postseismic deformation. The viscosity estimated from this model varies with material parameters (e.g. grain size, water content, etc.) as well as environmental parameters (temperature, pressure, background strain rate, etc.). The diffusion creep refers to the power law flow mainly controlled by the mineral grain size, and the dislocation creep refers to it mainly controlled by the background stress level. For a diffusion creep type of power law flow, a Tibetan crust composed of wet feldspar (water content = 1000 H/106Si; grain size = 1 - 4 mm) and upper mantle composed of wet olivine (water content = 200 H/106Si; grain size = ~2 mm) can predict the 6-year-long poseismic time series well. This result roughly agrees with rock mechanics laboratory experiments. The channel flow model predicts the plateau margins are steepest where the viscosity of the surrounding blocks are highest. The low viscosity in the Tibetan lower crust and the contrasting rheology across the plateau margin derived from postseismic deformation are consistent with the channel flow model.

Exciting developments in earthquake science have benefited from new observations, improved computational technologies, and improved modeling capabilities. Designing models of the earthquake generation process is a grand scientific challenge due to the complexity of phenomena and range of scales involved from microscopic to global. Such models provide powerful new tools for the study of earthquake precursory phenomena and the earthquake cycle. Through workshops, collaborations and publications, the APEC Cooperation for Earthquake Simulations (ACES) aims to develop realistic supercomputer simulation models for the complete earthquake generation process, thus providing a "virtual laboratory" to probe earthquake behavior. Part II of the book embraces dynamic rupture and wave propagation, computational environment and algorithms, data assimilation and understanding, and applications of models to earthquakes. This part also contains articles on the computational approaches and challenges of constructing earthquake models.

Geodesy, which is the science of measuring the size and shape of the Earth, explores the theory, instrumentation and results from modern geodetic systems. The beginning sections of the volume cover the theory of the Earth's gravity field, the instrumentation for measuring the field, and its temporal variations. The measurements and results obtained from variations in the rotation of the Earth are covered in the sections on short and long period rotation hanges. Space based geodetic methods, including the global positioning system (GPS) and Interferometric synthetic aperture radar (SAR), are also examined in detail. Self-contained volume starts with an overview of the subject then explores each topic with in depth detail Extensive reference lists and cross references with other volumes to facilitate further research Full-color figures and tables support the text and aid in understanding Content suited for both the expert and non-expert

Geodesy is the science of accurately measuring and understanding three fundamental properties of Earth: its geometric shape, its orientation in space, and its gravity field, as well as the changes of these properties with time. Over the past half century, the United States, in cooperation with international partners, has led the development of geodetic techniques and instrumentation. Geodetic observing systems provide a significant benefit to society in a wide array of military, research, civil, and commercial areas, including sea level change monitoring, autonomous navigation, tighter low flying routes for strategic aircraft, precision agriculture, civil surveying, earthquake monitoring, forest structural mapping and biomass estimation, and improved floodplain mapping. Recognizing the growing reliance of a wide range of scientific and societal endeavors on infrastructure for precise geodesy, and recognizing geodetic infrastructure as a shared national resource, this book provides an independent assessment of the benefits provided by geodetic observations and networks, as well as a plan for the future development and support of the infrastructure needed to meet the demand for increasingly greater precision. Precise Geodetic Infrastructure makes a series of focused recommendations for upgrading and improving specific elements of the infrastructure, for enhancing the role of the United States in international geodetic services, for evaluating the requirements for a geodetic workforce for the coming decades, and for providing national coordination and advocacy for the various agencies and organizations that contribute to the geodetic infrastructure.

Satellite remote sensing is the primary tool for measuring global changes in the land, ocean, biosphere, and atmosphere. Over the past three decades, active remote sensing technologies have enabled increasingly precise measurements of Earth processes, allowing new science questions to be asked and answered. As this measurement precision increases, so does the need for a precise geodetic infrastructure. Evolving the Geodetic Infrastructure to Meet New Scientific Needs summarizes progress in maintaining and improving the geodetic infrastructure and identifies improvements to meet new science needs that were laid out in the 2018 report Thriving on Our Changing Planet: A Decadal Strategy for Earth Observation from Space. Focusing on sea-level change, the terrestrial water cycle, geological hazards, weather and climate, and ecosystems, this study examines the specific aspects of the geodetic infrastructure that need to be maintained or improved to help answer the science questions being considered.

The study of the seismic cycle has many applications, from the study of faulting to the estimation of seismic hazards. It must be considered at different timescales, from that of an earthquake, the co-seismic phase (a few seconds), the post seismic phase (from months to dozens of years) and the inter-seismic phase (from dozens to hundreds of years), up to cumulative deformations due to several seismic cycles (from a few thousand to hundreds of thousands of years). The Seismic Cycle uses many different tools to approach its subject matter, from short-term geodesic, such as GPS and InSAR, and seismological observations to long-term tectonic, geomorphological, morphotectonic observations, including those related to paleoseismology. Various modeling tools such as analog experiences, experimental approaches and mechanical modeling are also examined. Different tectonic contexts are considered when engaging with the seismic cycle, from continental strike-slip faults to subduction zones such as the Chilean, Mexican and Ecuadorian zones. The interactions between the seismic cycle and magmatism in rifts and interactions with erosion in mountain chains are also discussed.