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Subduction Zone Earthquake and Tsunami

Diagram showing the mechanism of subduction zone earthquake and tsunami generation. There are 3 panels showing relationship between crust of subducting and overriding plates. Three panels include the following text (1) OVERALL, a tectonic plate descends, or “subducts,” beneath and adjoining plate. But it does so in a stick-slip fashion. (2) BETWEEN EARTHQUAKES the plates slide freely at great depth, where hot and ductile. But at shallow depth, where cool and brittle, they stick together. Slowly squeezed, the overriding plate thickens. (3) DURING AN EARTHQUAKE the leading edge of the overriding plate breaks free, spring seaward and upward. Behind, the plate stretches; its surface falls. The vertical displacements set off a tsunami.

. Diagram showing the mechanism of subduction zone earthquake and tsunami generation. When the subduction zone is locked, inboard portions of the upper plate are pushed upward by a build-up of tectonic stress. This is why the outer coast of the Kenai Peninsula is currently moving upward (see Figure 33). However, once the stress is released in the form of an earthquake, this same area that was moving upward rapidly subsides.

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Modified from Atwater et al. (2005).

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Kenai Fjords National Park, Code: KEFJ

Kenai Fjords National Park, Kenai Peninsula Borough, Alaska
Latitude: 59.9532012939453, Longitude: -149.88200378418

NPS.gov Collection

01/01/0001

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Brian F. Atwater

Monday, August 16, 2021 1:54:51 PM

Monday, August 16, 2021 4:00:35 PM

Fig_32_subduction_EQ_deformation_mechanism_KEFJ.jpg

Monday, January 1, 0001 12:00:00 AM

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