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Small Earthquake Registered At Mount St. Helens With PM-Earthquake, Bjt

October 2, 1987

SEATTLE (AP) _ A small earthquake shook the Mount St. Helens area 13 hours after a powerful temblor caused widespread destruction in Southern California, but the timing was most likely coincidental, officials said.

The temblor hit the volcano area at 8:38 p.m. and registered between 2.5 and 2.8 on the Richter scale, said University of Washington seismologist Linda Noson.

She said the quake was not linked to volcanic activity, and ″quite unliklely″ related to the one near Los Angeles.

″It’s a little distant for that kind of one-two punch,″ she said.

Mount St. Helens first stirred to life in this century in March 1980. Its May 18, 1980, eruption leveled 230 square miles, left 57 people dead or missing and sent up an ash cloud that circled the globe.

The last eruption at the volcano was Oct. 21-23, 1986, when a new lobe of molten rock spread out on top of the lava dome.

The Richter scale is a measure of ground motion in which each increase of one number means a tenfold increase in magnitude. Thus a reading of 7.5 reflects an earthquake 10 times stronger than one of 6.5.

An earthquake of 3.5 on the Richter scale can cause slight damage in a local area.

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