© U.S. Geological Survey via Getty Images
A plume of condensation rises off Mount St. Helens, as viewed from the roof of the Cascades Volcano Observatory December 19, 2006, in Vancouver, Washington.
A plume of condensation rises off Mount St. Helens, as viewed from the roof of the Cascades Volcano Observatory December 19, 2006, in Vancouver, Washington.
The 3.9 magnitude earthquake was felt in Portland but there were no reported injuries or damage. Since that earthquake there have been 16 more earthquakes, averaging about every half hour with magnitudes from 0.6 to 2.6.
It is common to experience swarms of earthquakes at Mount St. Helens. While it is certainly not a sign of an impending eruption, the earthquakes are a result of an active volcanic system.
Comment: It seems that swarms of earthquakes in the area are a more recent development and were not so common in previous years.
Mount St. Helens is most commonly known for its major eruption in 1980, the deadliest and most economically damaging volcanic event in the history of the United States. The stratovolcano is situated just 96 miles from Seattle and 50 miles from Portland, making an eruption especially dangerous.
Comment: In recent years there has been much activity in the surrounding area and the recent quakes are said to be related to magma movement underground. See also: