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Earthquake swarm shakes Maupin, Oregon

Oregon, USA
Earthquake swarm shakes Maupin. During the last two years more than 350 small earthquakes have been recorded just outside the small eastern Oregon town of Maupin, and scientists are unsure what is triggering the activity.The earthquakes began in December of 2006 and though only a dozen or so of the temblors exceeded magnitude 3.0, the largest of the events could be felt locally. The earthquakes all originated within a very small area just a few miles southeast of Maupin and about 30 miles southeast of Mt. Hood. Seismic activity in eastern Oregon is comparatively rare and when it does happen, it seems like it happens in these swarms. More common earthquake activity is to get a main shock and then a number of aftershocks. But these swarms lack a main event and instead are characterized by an ongoing series of small quakes. These small earthquakes strike Maupin about every other day on average and one looks a lot like another. Occasionally, two or three quakes would occur on the same day, but never more than four. And rarely would more than a few days go by without an earthquake. That's RATHER UNUSUAL. A geologic map shows a small fault line near the region where most of the quakes have occurred, though it runs in a direction that doesn’t necessarily mirror the pattern of recorded earthquakes. “You think at some point that the earthquakes are done, but they keep cranking along. It isn’t likely that a major quake will follow, but you can never exclude that possibility. That uncertainty is why we need to do more research.”
A similar swarm of earthquakes, though some of them larger, has been taking place in Reno, which also is along the Eastern California Shear Zone. Those quakes are much shallower; about two miles below the surface compared to the 10 mile-deep Maupin events.
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