Tsunami Warning – Pacific Region

On February 27th, 2010, at 03:34 AM local time (February 27th, 2010, at
06:34 AM UTC) an earthquake occurred at the coast of Chile, near the city
Concepcion, with a magnitude Mw 8.8 in a depth of about 35 kilometres.
Because of the earthquake magnitude and the relatively shallow location of
the epicentre, there was a concrete danger of a destructive tsunami.
Therefore, the subscribers of the Tsunami Alarm System were informed of the
event shortly after the earthquake. (we will send a detailed report soon)

Geological background: This earthquake occurred at the boundary between the
Nazca and South American tectonic plates. The two plates are converging at
a rate of 80 mm per year. The earthquake occurred as thrust-faulting on the
interface between the two plates, with the Nazca plate moving down and
landward below the South American plate. Coastal Chile has a history of
very large earthquakes. Since 1973, there have been 13 events of magnitude
7.0 or greater. The February 27 shock originated about 230 km north of the
source region of the magnitude 9.5 earthquake of May, 1960 – the largest
instrumentally recorded earthquake in the world. This magnitude 9.5
earthquake killed 1655 people in southern Chile and unleashed a tsunami
that crossed the Pacific, killing 61 people in Hawaii, Japan, and the
Philippines. Approximately 870 km to the north of the February 27
earthquake is the source region of the magnitude 8.5 earthquake of November,
1922. This great quake significantly impacted central Chile, killing
several hundred people and causing severe property damage. The 1922 quake
generated a 9-meter local tsunami that inundated the Chile coast near the
town of Coquimbo; the tsunami also crossed the Pacific, washing away boats
in Hilo harbor, Hawaii. The magnitude 8.8 earthquake of February 27, 2010
ruptured the portion of the South American subduction zone separating these
two massive historical earthquakes. A large vigorous aftershock sequence
can be expected from this earthquake.

Tsunami Institute Team

Tsunami Institute Tuebingen, Germany
United States Geological Service (2010): Earthquake Summary.
2010 February 27th

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