Evaluation of One-Dimensional Seismic Site Response Analyses at Small to Large Strain Levels

Thesis (Master's)--University of Washington, 2016-08

Using Geophysical Tools to Resolve Areas of Seismic Ambiguity

The flanks of an oil-bearing structure were investigated to determine the most likely reservoir geometry in an area where the seismic path forks in preparation for a field equity redetermination. Two alternate hypotheses were evaluated: a “high fork model” where the reservoir top follows the higher of the two paths and a “low fork model” in which the reservoir follows the lower path. I took four approaches to evaluate the hypotheses: 1) Depth conversion by multiple velocity models to evaluate the fidelity of the picked horizon on models that did not contain a fork; 2) hand interpretation around the areas of high uncertainty to eliminate their influence; 3) path choice effects on the plausibility of the environment of deposition; and subsurface geometry modeling with synthetics to compare calculated 1D seismic responses with current data. Investigation established that both fork interpretations cannot follow a continuous seismic reflector but are otherwise equally plausible. Interval modeling revealed several structure scenarios, supporting both high and low fork, which fit the seismic data. To augment the lower fork argument, a scenario with an additional sand interval off-structure is recommended, for simplicity and reasonability.

Locating the Seattle Fault in Bellevue, WA: Combining geomorphic indicators with borehole data

The Seattle Fault is an active east-west trending reverse fault zone that intersects both Seattle and Bellevue, two highly populated cities in Washington. Rupture along strands of the fault poses a serious threat to infrastructure and thousands of people in the region. Precise locations of fault strands are still poorly constrained in Bellevue due to blind thrusting, urban development, and/or erosion. Seismic reflection and aeromagnetic surveys have shed light on structural geometries of the fault zone in bedrock. However, the fault displaces both bedrock and unconsolidated Quaternary deposits, and seismic data are poor indicators of the locations of fault strands within the unconsolidated strata. Fortunately, evidence of past fault strand ruptures may also be recorded indirectly by fluvial processes and should also be observable in the subsurface. I analyzed hillslope and river geomorphology using LiDAR data and ArcGIS to locate surface fault traces and then compare/correlate these findings to subsurface offsets identified using borehole data. Geotechnical borings were used to locate one fault offset and provide input to a cross section of the fault constructed using Rockworks software. Knickpoints, which may correlate to fault rupture, were found upstream of this newly identified fault offset as well as upstream of a previously known fault segment.

Seismic Evaluation and Retrofit of Concentrically Braced Frames

Thesis (Master's)--University of Washington, 2016-06

Design Expressions and Dynamic Evaluation of CFST Bridges Subjected to Seismic Hazards

Thesis (Ph.D.)--University of Washington, 2016-06

Seismically-Induced Rock-Slope Failure: Numerical Investigation using the Bonded Particle Model

Thesis (Ph.D.)--University of Washington, 2016-06