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Scientists Blow Up Dynamite In Study of Quake Fault

November 8, 1987

SOUTH EL MONTE, Calif. (AP) _ Residents were awakened early Sunday by what some thought was an earthquake when scientists blew up 1,200 pounds of dynamite underground to study the fault that caused last month’s powerful temblor.

The 4:10 a.m. blast near the epicenter of the Oct. 1 earthquake that killed seven people, was felt in nearby towns, including Whittier, Rosemead and Temple City, authorities said.

U.S. Geological Survey scientists placed the explosives in a 330-foot hole drilled in the Whittier Narrows Recreation Area, about 12 miles east of Los Angeles, to measure shock waves from the blast at surrounding points.

Scientists said the controlled explosion would help them learn more about why and how earthquakes happen.

Seismologists had said the force of the blast would be felt no farther than 100 yards from the site.

″It just felt like a rumble here, but our phones lit up like there was no tomorrow ... people calling saying ’We had another earthquake,‴ said Los Angeles County sheriff’s Deputy Jerry Trueman at the Temple City station.

The ground motion from the blast registered 1.7 on the Richter scale at the California Institute of Technology in Pasadena, said seismic analyst Steve Bryant.

The blast triggered burglar alarms in the Temple City area, Deputy Doug Gatlin said.

In Whittier, police received a few calls from people who said they had felt the blast, said dispatcher Scott Eldridge. ″It was definitely more than the 100 yards they said it would be,″ he said.

Seismologists had assured residents the explosion would not trigger another earthquake.

″Geologists exploring for oil set off hundreds of such explosions around the United States every week, and none has ever set off an earthquake,″ said Lucille M. Jones of the U.S. Geological Survey.

The Oct. 1 temblor, which registered 5.9 on the Richter scale of ground motion, and its aftershocks caused more than $213 million in damage, primarily in suburbs east of Los Angeles.

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