Feds seek public help in understanding quakes


The U.S. Geological Service wants the public's help in understanding how close-to-home earthquakes feel.

A recent 3.9 quake near Maupin yielded few reports from nearby residents. A USGS Web site, http:pasadena.wr.usgs.gov/shake/pnw/, has a place for comments and asks questions that help characterize the quake experience.

The Maupin area has had a swarm of small quakes for about the last two years, said Evelyn Roeloffs, a geophysicist at the USGS.

She said she doesn't know why but that it's not the first time.

A 4.8 magnitude earthquake hit there on April 12, 1976, Roeloffs noted, referring to an Oregon State University report.

Houses "shook, swayed, rattled, creaked and rocked" and sounds similar to thunder or sonic booms accompanied it, according to the report.

People reported feelings of queasiness, cracked plaster and falling objects.

That quake was also apparently part of a longer swarm, Roeloffs said.

She offered one theory.

"Some geologists feel that the tectonic setting of the Maupin area will at some time far in the future look a bit more like, for example, Lakewood in southern Oregon," she said.

The Lakeview area features a series of lakes and big upthrown fault escarpments. It's part of a geological area that covers most Nevada and appears to be moving north.

"It tends to have earthquake swarms of this type," Roeloffs said.

The tectonic action often happens over tens of thousands or hundreds of thousands of years, she said.

She said the ability to record smaller quakes has improved but that the recent Maupin quake would have been recorded at any time in the last 15 years.

"Its definitely not an artifact of improved instrumentation," she said.

She said she is often asked if there will be others and she says it is a fair bet that there will be, as big or bigger than the intensity of 3.9.

She said there is no history of quakes in the area big enough to do significant damage. "Nevertheless, one should always be prepared."

She emphasized the value of witness reports ad urged people in the area to report their observations.

"It helps keep peoples awareness up," she said.

"And the information is very much used in helping determine how much an earthquake of a certain size shakes. And that factors into building codes."

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