Re-examination of the Potential for Great Earthquakes along the Aleutian Island Arc with Implications for Tsunamis in Hawaii

Abstract

Hawaii is threatened by tsunamis from circum-Pacific earthquakes and has been hit by major tsunamis from great earthquakes in the prior century in Kamchatka (1952), the Aleutians (1946 and 1957), Chile (1960), and Alaska (1964). Of these, tsunamis generated from great earthquakes along the Alaska-Aleutian Island arc are of particular concern due to their short (4.5–hour) propagation time to Hawaii, which presents the most limited time for coastal evacuation. Historically, the Aleutian earthquakes of 1946 and 1957 produced the largest tele-tsunamis observed in Hawaii (Lander and Lockridge 1989). The 1946 event ( Mw 8.6) killed 159 people with waves reaching up to 16 m height on Molokai. Even though the 1957 event ( Mw 8.6) caused no deaths in Hawaii, a maximum run-up of 16 m was observed on Kauai. Although these two great earthquakes in the Aleutians had substantial tsunami impacts in Hawaii, they are not among the largest seismic events to have occurred globally in the last century. To evaluate the extent of the tsunami threat to Hawaii from the Aleutian Islands, we need to consider the potential for even larger earthquakes in light of the analysis of more than a century of data measuring the Aleutian seismic zone. The motivation for this review is the great Tohoku earthquake of 2011, which occurred in the active seismic region off the coast of East Honshu, Japan, and caused a deadly tsunami in Japan that was felt on shorelines across the Pacific. This magnitude Mw 9.0 event surprised the seismological community with respect to its unexpectedly large magnitude and the size of the generated tsunami ( e.g. , Normile 2011; Monastersky 2011; Showstack 2011). Since the great Sanriku earthquake of 1896 there have been nine damaging earthquakes (magnitude M 7.3 to about 8.6) in the area of the Tohoku earthquake rupture …