PNNL

Abstract

The Three Sisters volcanoes in the central Oregon Cascade Range are in the news again. Near the end of March there were about 100 small earthquakes that occurred 3 miles west of South Sister. The US Geological Survey attributed the earthquakes to a ‘modest amount of magma’ accumulating at a depth of about 4 miles. The magma also has caused about 10 inches of uplift there since 1997. Geologists are now trying to determine what this really means to the area. Are we seeing the beginning phase of a future eruption or is it simply just a normal event in the life of a young volcano? This is a newspaper article about the Three Sisters volcanoes