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How Extinct Undersea Volcanoes Trigger Rare ‘Tsunami Earthquakes’
by Kelly Dickerson | June 30, 2014 02:42pm ET
| Tsunamis, like the one that stuck Aceh, Indonesia, can cause serious flooding and submerge entire villages.
Credit: United States Navy
How unusual slow earthquakes can spawn powerful tsunamis is a long-standing mystery that researchers may have finally solved.
Called “tsunami earthquakes,” these slow quakes are capable of creating huge waves that can cause serious damage to coastal cities. Tsunami earthquakes are not like typical earthquakes. They happen slowly and don’t generate the same kind of violent shaking as typical earthquakes — the tell-tale sign that it’s time to evacuate.
Scientists first discovered tsunami earthquakes 35 years ago and they happen so rarely there has been little opportunity to study them since. Now, a new study suggests that tsunami earthquakes happen when two sections of Earth’s crust, called tectonic plates, get hung up on extinct volcanoes on the ocean floor, called seamounts. The seamounts act like tread on a tire and make tectonic plates stick. [The 10 Biggest Earthquakes in History]