Thesis (M.App.Sc.) - Carleton University, 2006. / Includes bibliographical references (p. 165-175). Also available in electronic format on the Internet.

Thesis (Ph. D.)--University of California, Riverside, 2009. / Includes abstract. Includes bibliographical references (leaves 112-120). Issued in print and online. Available via ProQuest Digital Dissertations.

Thesis (M.S.)--Oregon State University, 2004. / Printout. Includes bibliographical references (leaves 155-158). Also available on the World Wide Web.

Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (leaves 265-276).

Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2006. / Mayne, Paul W., Committee Chair ; Goldsman, David, Committee Member ; Lai, James, Committee Member ; Rix, Glenn J., Committee Member ; Santamarina, J. Carlos, Committee Member.

abstract: The dynamic Earth involves feedbacks between the solid crust and both natural and anthropogenic fluid flows. Fluid-rock interactions drive many Earth phenomena, including volcanic unrest, seismic activities, and hydrological responses. Mitigating the hazards associated with these activities requires fundamental understanding of the underlying physical processes. Therefore, geophysical monitoring in combination with modeling provides valuable tools, suitable for hazard mitigation and risk management efforts. Magmatic activities and induced seismicity linked to fluid injection are two natural and anthropogenic processes discussed in this dissertation. Successful forecasting of the timing, style, and intensity of a volcanic eruption is made possible by improved understanding of the volcano life cycle as well as building quantitative models incorporating the processes that govern rock melting, melt ascending, magma storage, eruption initiation, and interaction between magma and surrounding host rocks at different spatial extent and time scale. One key part of such models is the shallow magma chamber, which is generally directly linked to volcano’s eruptive behaviors. However, its actual shape, size, and temporal evolution are often not entirely known. To address this issue, I use space-based geodetic data with high spatiotemporal resolution to measure surface deformation at Kilauea volcano. The obtained maps of InSAR (Interferometric Synthetic Aperture Radar) deformation time series are exploited with two novel modeling schemes to investigate Kilauea’s shallow magmatic system. Both models can explain the same observation, leading to a new compartment model of magma chamber. Such models significantly advance the understanding of the physical processes associated with Kilauea’s summit plumbing system with potential applications for volcanoes around the world. The unprecedented increase in the number of earthquakes in the Central and Eastern United States since 2008 is attributed to massive deep subsurface injection of saltwater. The elevated chance of moderate-large damaging earthquakes stemming from increased seismicity rate causes broad societal concerns among industry, regulators, and the public. Thus, quantifying the time-dependent seismic hazard associated with the fluid injection is of great importance. To this end, I investigate the large-scale seismic, hydrogeologic, and injection data in northern Texas for period of 2007-2015 and in northern-central Oklahoma for period of 1995-2017. An effective induced earthquake forecasting model is developed, considering a complex relationship between injection operations and consequent seismicity. I find that the timing and magnitude of regional induced earthquakes are fully controlled by the process of fluid diffusion in a poroelastic medium and thus can be successfully forecasted. The obtained time-dependent seismic hazard model is spatiotemporally heterogeneous and decreasing injection rates does not immediately reduce the probability of an earthquake. The presented framework can be used for operational induced earthquake forecasting. Information about the associated fundamental processes, inducing conditions, and probabilistic seismic hazards has broad benefits to the society. / Dissertation/Thesis / Doctoral Dissertation Geological Sciences 2018

Caldera systems such as Long Valley Caldera, California; Taupo, New Zealand; and Campi Flegrei, Italy, experience centuries to millennia without eruption, but have the potential for large eruptions. This raises questions about how local residents' behavioral responses to these low-probability high-consequence events differ from their responses to events, such as wildfires and earthquakes, that have higher probabilities. To examine this issue, a multi-hazard mail survey of 229 households explored perceptions of—and responses to—volcano, earthquake and wildfire hazards in the Long Valley Volcanic Region. Response efficacy was the only significant predictor of emergency preparedness, which suggests that hazard managers can increase household emergency preparedness by emphasizing this attribute of protective actions. In addition to response efficacy, expected personal consequences, hazard intrusiveness, and affective responses were all significantly related to information seeking. This indicates that hazard managers can also increase households’ information seeking about local hazards and appropriate protective actions by communicating the certainty and severity of hazard impacts (thus increasing expected personal consequences) and that they communicate this information repeatedly (thus increasing hazard intrusiveness) to produce significant emotional involvement (thus increasing affective response).

Numerous observations suggest that the elastic description of the subduction earthquake cycles is incomplete. Micro-seismicity is recorded in active margins that are believed to be locked, while peculiar extensional earthquakes occur in convergent plate boundaries following tsunami earthquakes. The morphology of active margins, which evolves on time scales of 100s of kyr, shows similarities to ongoing deformation documented over 10–100 yrs and the coastal domains of Cascadia, Chile, and other subduction zones record long-term uplift. Lastly, the very threshold where faults break and earthquake nucleate has been vigorously debated for years. In this thesis, I combine various geophysical tools to study short- and long-term processes and learn how their interplay can shape the deformation field imparted by earthquake cycles, mainly in the upper plate of subduction zones. In the first chapter, I analyze surface heat flow measurements taken in the proximity of the southern Dead Sea fault to demonstrate its friction is 0.27±0.17. In the second chapter, I compute an updated horizontal and vertical GNSS velocity field for Bangladesh, Myanmar, and adjacent regions. I show that the Kabaw fault, which lies east of the primary thrust system, is accommodating shortening that was initially attributed to the main thrust and demonstrate that the Indo-Burma subduction is locked, converging, and capable of hosting great megathrust events. In the third chapter, I use thermomechanical models to show that reducing the dip angle of a subducting slab, on a timescale of millions of years, can result in extensional fault failure above a megathrust earthquake on timescales of seconds to months. In the fourth chapter, I demonstrate how the buildup of interseismic elastic stresses brings sections of the forearc into compressional failure, which yields irreversible uplift of the coastal domain per evidence from Chile. Finally, I argue that combining short- and long-term processes into subduction zone models can better mitigate tsunami and earthquake hazards. I show how long-term reduction of slab dip angle could culminate in devastating tsunamis. I argue that the collection of long-term uplift records of upper plates or volcanic arc migration can constrain slab dip changes and so may identify areas with increased tsunami potential. In addition, upper plate irreversible deformation should be introduced to earthquake rupture models as these may hold significant implications for understanding and mitigating earthquake hazards.

This study examines the sensitivity of calculated site response in connection with alternative assumptions regarding input motions and procedures prescribed in the IBC 2000 building code, particularly the use of average shear wave velocity in the upper 30 meters as an index for engineering design response spectra. Site specific subsurface models are developed for four sites in and near Columbia, South Carolina using shear wave velocity measurements from cone penetrometer tests. The four sites are underlain by thin coastal plain sedimentary deposits, overlying high velocity Paleozoic crystalline rock. An equivalent-linear algorithm is used to estimate site response for vertically incident shear waves in a horizontally layered Earth model. Non-linear mechanical behavior of the soils is analyzed using previously published strain-dependent shear modulus and damping degradation models. Two models for material beneath the investigated near-surface deposits are used: B-C outcrop conditions and hard rock outcrop conditions. The rock outcrop model is considered a geologically realistic model where a velocity gradient, representing a transition zone of partially weathered rock and fractured rock, overlies a rock half-space. Synthetic earthquake input motions are generated using the deaggregations from the 2002 National Seismic Hazard Maps, representing the characteristic Charleston source. The U. S. Geological Survey (2002) uniform hazard spectra are used to develop 2% in 50 year probability of exceedance input ground motions for both B-C boundary and hard rock outcrop conditions. An initial analysis was made for all sites using an 8 meter thick velocity gradient for the rock input model. Sensitivity of the models to uncertainty of the weathered zone thickness was assessed by randomizing the thickness of the velocity gradient. The effect of the velocity gradient representing the weathered rock zone increases site response at high frequencies. Both models (B-C outcrop conditions and rock outcrop conditions) are compared with the International Building Code (IBC 2000) maximum credible earthquake spectra. The results for both models exceed the IBC 2000 spectra at some frequencies, between 3 and 10 Hz at all four sites. However, site 2, which classifies as a C site and is therefore assumed to be the most competent of the four sites according to IBC 2000 design procedures, has the highest calculated spectral acceleration of the four sites analyzed. Site 2 has the highest response because a low velocity zone exists at the bottom of the geotechnical profile in immediate contact with the higher velocity rock material, producing a very large impedance contrast. An important shortcoming of the IBC 2000 building code results from the fact that it does not account for cases in which there is a strong rock-soil velocity contrast at depth less than 30 meters. It is suggested that other site-specific parameters, specifically, depth to bedrock and near-surface impedance ratio, should be included in the IBC design procedures. / Master of Science

Events or forces of nature with catastrophic consequences, or "natural disasters," have increased in both frequency and force due to climate change and increased urbanization in climate-sensitive areas. To create capacity to face these dangers, an entity must first quantify the threat and translate scientific knowledge on nature into comprehensible estimates of cost and loss. These estimates equip those at risk with knowledge to enact policy, formulate mitigation plans, raise awareness, and promote preparedness in light of potential destruction. Hazards-United States, or Hazus, is one such tool created by the federal government to estimate loss from a variety of threats, including earthquakes, hurricanes, and floods. Private and governmental agencies use Hazus to provide information and support to enact mitigation measures, craft plans, and create insurance assessments; hence the results of Hazus can have lasting and irreversible effects once the hazard in question occurs. This thesis addresses this problem and sheds light on the obvious and deterministic failings of Hazus in the context of the probable earthquake in Portland, OR; stripping away the tool's black box and exposing the grim vulnerabilities it fails to account for. The purpose of this thesis is twofold. First, this thesis aims to examine the critical flaws within Hazus and the omitted vulnerabilities particular to the Portland region and likely relevant in other areas of study. Second and more nationally applicable, this thesis intends to examine the influence Hazus outputs can have in the framing of seismic risk by the non-expert public. Combining the problem of inadequate understanding of risk in Portland with the questionable faith in Hazus alludes to a larger, socio-technical situation in need of attention by the academic and hazard mitigation community. This thesis addresses those issues in scope and adds to the growing body of literature on defining risk, hazard mitigation, and the consequences of natural disasters to urban environments.