Field Observations and Modeling of Tsunamis on the Islands of the Four Mountains, Aleutian Islands, Alaska

Frances Griswold
May 2014

Purpose and Introduction

Adequate geophysical and historical information for assessing the potential danger of earthquakes and accurately predicting patterns of rupture do not exist for the Aleutian subduction zone. The historical records and eyewitness accounts are sparse, and the paleotsunami record is unstudied. To accurately assess the tsunami hazard facing countries throughout the Pacific Ocean because of the Aleutian subduction zone, the seismic history of the arc needs to be better documented and quantified. To document the frequency and magnitude of tsunamis along the Aleutian subduction zone, particularly near the Islands of the Four Mountains (IFM), I will identify paleotsunami, the 1946 tsunami, and the 1957 tsunami deposits in the field. I will then model these events using GeoClaw, a two-dimensional, shallow wave, open-source software package to determine the magnitude of earthquakes that can produce the identified tsunami deposits. By combining field and modeling components I will produce first-order estimates of how often and how large past earthquakes and subsequent tsunamis were along the eastern segment of the Aleutian subduction zone, specifically in the vicinity of IFM. The eastern Aleutians is an important place to conduct paleotsunami studies because the directionality of the eastern segment of the subduction zone, that is the direction of tsunami propagation, poses a great threat to countries across the Pacific and the west coast of the continental U.S. in particular.

Full Thesis Proposal (PDF format)