Thursday, February 17, 2011

Mt St Helens Volcano, USA - John Seach

A swarm of earthquakes hit Mt St Helens volcano on 14th February 2011. The earthquakes were centered in an area near the Johnston Ridge Observatory, about 7 km north of the crater. The earthquakes had a focus at a depth of about 2-4 km. At least 12 small earthquakes were measured in the area since Monday. The initial earthquake was the largest with a magnitude of 4.3 and hit around 10:35 a.m. local time. The earthquakes are possibly caused by fault movement under the volcano as a result of magma removal during the 1980 eruption. Earthquake swarms occurred in the same area in January 2011 and August 1980. The USGS stated "at present there appears to be no signs of unrest in the volcanic system". The current volcano alert level for Mount St. Helen's remains at normal.
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