Impact tsunami–EltaninAbstract: Employing classical tsunami theory and elementary assumptions about the initial shape of impact cavities, we compute tsunami from the Eltanin asteroid collision at 2.15 Ma. An Eltanin impactor 4 km in diameter would have blown an initial cavity as deep as the ocean and 60 km wide into the South Pacific and delivered a 200–300 m high tsunami to the Antarctic Peninsula and the southern tip of South America 1200–1500 km away. New Zealand, 6000 km distant, would have met 60 m waves. Generalizing these results to other size impactors, we fit simplified tsunami attenuation laws to maximum tsunami heights extracted from the full-wave calculations. If Eltanin was 1 km in diameter instead of 4 km, its waves would have been at least five times smaller. An asteroid the size of Chicxulub (10 km diameter), had it fallen into water deeper than 1000 m, would have sent a 100 m tsunami out to 4000 km distance, even if shoaling amplifications are neglected.
Steven N. Ward
Erik Asphaug
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