2 Sep 11 – The newly discovered fault stretches about 20 miles (32.2 km) from the northern flank of Mount Hood to the Columbia River.
The fault appears to have been recently active, and could be an earthquake threat today, reports the Portland Oregonian.
Scientists said the last time the fault ruptured, possibly during a magnitude 6 or 7 earthquake, the ground ripped six feet (1.8 meters) apart leaving a miles-long raised edge, or scarp.
Researchers from the Oregon Department of Geology and Mineral Industries are now working to estimate the threat that the fault poses to nearby communities.
Mount Hood has grown in fits and starts with decades to centuries of frequent eruptions separated by quiet periods lasting from centuries to more than 10,000 years, says the USGS. In the recent past, Mount Hood has had two significant eruptive periods, one about 1,500 years ago and the other about 200 years ago.
Mount Hood, the tallest mountain in Oregon, does not have a history of violent explosive eruptions. Instead, lava flows, rarely traveling more than 6 to 8 miles from their source, have built up the flanks of the volcano one sector at a time.
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