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Great Aleutian Tsunami and New Extreme Tsunami Evacuation Zones (XTEZ)


XTEZ Refuges Areas & Routes: O’ahu Coastal Communities Evacuation Planning Project

The 2011 Tohoku earthquake and tsunami in Japan spurred interest in investigating other regions around the Pacific for potential to generate large tsunamis beyond the historical record. The intent of this research was to investigate and assess the extent of a large tsunami that may impact the State of Hawai‘i that exceeds the historical record of tsunami events in the region. The historical tsunami events affecting Hawai‘i occurred in 1946, 1952, 1957, 1960, 1964 and 2011, with other statewide warnings from 2010-2013.

Geophysicists at the University of Hawai‘i have identified a possible source region in the Eastern Aleutian (EA) island arc, directly north of Hawai‘i, that has the potential for a very large magnitude 9+ earthquake that could produce a Great Aleutian Tsunami (GAT). Based on geophysical research and subsequent computer modeling of inundation, new tsunami inundation maps have been produced to indicate the maximum extent of the GAT inundation. The GAT inundation maps have been used to determine a new Extended Tsunami Evacuation Zone (XTEZ). The XTEZ will serve as a second evacuation zone for only a GAT scenario, all other tsunami events will continue to use the existing updated 2010 tsunami evacuation maps.