Local and trans-oceanic tsunamis in the Bering and Chukchi seas based on numerical modeling

Abstract

Abstract We have examined the tsunami risk in the Bering and Chukchi seas by determining whether trans-oceanic tsunamis penetrate into these regions through the Aleutian Islands and Bering Strait. Results are based on numerical modeling of eight major far-field earthquakes in the North Pacific Ocean and one near-field earthquake that occurred in the Bering Sea region: the 1946 Aleutian, 1952 Kamchatka, 1960 Chile, 1964 Alaska, 1965 Rat Islands, 1957 Andreanof Islands, 2011 Tohoku, 2012 Haida Gwaii, and 2017 Commander Islands earthquakes. It was found that the most powerful event to impact the Bering Sea was the 1960 tsunami generated by the Mw 9.5 Chilean earthquake. According to our numerical simulations, the 1960 earthquake produced tsunami waves with amplitudes up to 192 cm in the sea, while for the next strongest event, the 1952 Kamchatka tsunami, the wave amplitudes were up to 177 cm. The 1964 Great Alaska earthquake (Mw 9.2) did not produce an intense tsunami in the Bering Sea because the lone and narrow southwestern extension of the Alaska Peninsula sheltered the region from incoming tsunami waves. Modeling further shows that, in separate bays, tsunami waves formed by strong distant earthquakes could reach 1‒1.5 m. Results show that the typical attenuation coefficient for the straits of the Aleutian Islands is 0.75, on average, while the corresponding coefficient upon transition from the Bering Sea to the Chukchi Sea through the Bering Strait is ~ 0.25. Based on these estimates, we conclude that tsunami penetration into the Arctic Ocean from remote sources in the Pacific is unlikely. Even for such powerful events as the 1960 Chilean tsunami, the tsunami wave amplitudes in the Chukchi Sea would not exceed a few centimeters.