Extinct undersea volcanoes squashed under Earth's crust cause tsunami earthquakes
Date: June 27, 2014
Source: Imperial College London
Summary: New research has revealed the causes and warning signs of rare tsunami earthquakes, which may lead to improved detection measures. The new study reveals that tsunami earthquakes may be caused by extinct undersea volcanoes causing a "sticking point" between two sections of Earth's crust called tectonic plates, where one plate slides under another.
"The researchers from Imperial College London and GNS Science in New Zealand used geophysical data collected for oil and gas exploration and historical accounts from eye witnesses relating to two tsunami earthquakes, which happened off the coast of New Zealand's north island in 1947. Tsunami earthquakes were only identified by geologists around 35 years ago, so detailed studies of these events are rare.
The team located two extinct volcanoes off the coast of Poverty Bay and Tolaga Bay that have been squashed and sunk beneath the crust off the coast of New Zealand, in a process called subduction.
The researchers suggest that the volcanoes provided a "sticking point" between a part of Earth's crust called the Pacific plate, which was trying to slide underneath the New Zealand plate. This caused a build-up of energy, which was released in 1947, causing the plates to "unstick" and the Pacific plate to move and the volcanoes to become subsumed under New Zealand. This release of the energy from both plates was unusually slow and close to the seabed, causing large movements of the sea floor, which led to the formation of very large tsunami waves.
All these factors combined, say the researchers, are factors that contribute to tsunami earthquakes. The researchers say that the 1947 New Zealand tsunami earthquakes provide valuable insights into what geological factors cause these events. They believe the information they've gathered on these events could be used to locate similar zones around the world that could be at risk from tsunami earthquakes. Eyewitnesses from these tsunami earthquakes also describe the type of ground movement that occurred and this provides valuable clues about possible early warning signals for communities."
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link to www.sciencedaily.com]
I've always wondered what was happening during these types of earthquakes, and why there are some large earthquakes that do not produce tsunamis..
Last Edited by Hijinnx on 06/28/2014 01:21 AM
