Evaluation of the Potential Geological and Socioeconomic Impacts of the Imminent Cascadia Megathrust Earthquake

The Cascadia Subduction Zone on the northwest coast of the United States poses the threat of a devastating megathrust earthquake and subsequent tsunami damaging coastal populations. This paper synthesizes literature to analyze the geologic and socioeconomic effects of this natural disaster, as well as examines the existing warning system infrastructure, and makes recommendations to mitigate the damage. In order to assess the geologic effects of a megathrust earthquake, I investigate the tectonic history, the role of episodic tremor and slip (ETS) in stress buildup, crustal architecture of the subduction zone, and analogous subduction zones such as Chile and Japan. This information is then used to assess the socioeconomic effects of a megathrust earthquake. Demographic, geographic, and temporal information of the coastline are used to assign relative vulnerabilities to individual communities, pinpointing the areas at highest risk. Both geologic and socioeconomic effects are incorporated into an evaluation of ShakeAlert, the warning system in development for Cascadia. Recommendations for preemptive measures and warning system design, such as a higher magnitude criterion and more densely spaced instrumentation, are made by incorporating all factors, as well as by comparing ShakeAlert to the effective early warning systems of Japan