CASCADES VOLCANO OBSERVATORY WEEKLY UPDATE

Friday, August 30, 2013 10:31 AM PDT

CASCADE RANGE VOLCANOES

Current Volcano Alert Level: NORMAL

Current Aviation Color Code: GREEN

Activity Update: All volcanoes in the Cascade Range of Oregon and Washington are at normal levels of background seismicity. These include Mount Baker, Glacier Peak, Mount Rainier, Mount St. Helens, and Mount Adams in Washington State; and Mount Hood, Mount Jefferson, Three Sisters, Newberry Volcano, and Crater Lake in Oregon.

Recent Observations: A small ongoing swarm of earthquakes located about 13 miles northwest of Mount St. Helens continued this week. As of today, 120 earthquakes have been detected since the swarm began on 08/02. The largest event was a M3.7 that occurred on 08/23. These earthquakes are interpreted to be regional tectonic events and not directly related to volcanic seismicity at Mount St. Helens, which remained at normal background levels. On the south side of Mount Hood this week there were 16 small earthquakes located in the Government Camp and Barlow Pass areas, the largest of which was a M2.0 on 08/26. Small tectonic earthquakes are common in these areas and these events are not interpreted to be unusual. Field crews performed maintenance at monitoring stations at Mount St. Helens and around the Three Sisters area and also conducted field investigations at Glacier Peak, Mount Hood, and Newberry Volcano.

The U.S. Geological Survey Cascades Volcano Observatory and the University of Washington continue to monitor the Washington and Oregon volcanoes closely and will issue additional updates and changes in alert level as warranted.

McKenzie River Reflections