Cascade Range Current Updates
June 2010

CASCADE RANGE VOLCANO
Current Volcano Alert Level: NORMAL
Current Aviation Color Code: GREEN

Activity Update: All volcanoes in the Cascade Range are at normal levels of background seismicity. These include Mount Baker, Glacier Peak, Mount Rainier, Mount St. Helens, and Mount Adams in Washington State; Mount Hood, Mount Jefferson, Three Sisters, Newberry Volcano, and Crater Lake, in Oregon; and Medicine Lake volcano, Mount Shasta, and Lassen Peak in northern California. Mount St. Helens has been at Volcano Alert Level NORMAL (Aviation Color Code GREEN) since July 10, 2008.

Recent Observations: Stations near the summit of Mount Rainier (see, for example, station RCS on the PNSN webicorder page) have recorded a series of very small earthquakes that have been occurring every 2-3 minutes since June 2nd. This sequence of earthquakes is similar to a sequence that occurred in May and which lasted for over a week. Similar earthquake sequences were reported by the PNSN in 1990 and 1998. These earthquakes are very shallow, are located beneath a glacier, and are interpreted to be glacial in origin. We continue to monitor the activity. Elsewhere, seismic activity and ground deformation at Cascade Range volcanoes have remained at background levels this week.

Cascade Range Volcanoes
Volcano Alert Level: NORMAL
Aviation Color Code: GREEN

Activity Update: All volcanoes in the Cascade Range are at normal levels of background seismicity. These include Mount Baker, Glacier Peak, Mount Rainier, Mount St. Helens, and Mount Adams in Washington State; Mount Hood, Mount Jefferson, Three Sisters, Newberry Volcano, and Crater Lake, in Oregon; and Medicine Lake volcano, Mount Shasta, and Lassen Peak in northern California. Mount St. Helens has been at Volcano Alert Level NORMAL (Aviation Color Code GREEN) since July 10, 2008.

Recent Observations: The very small, very shallow earthquakes, thought to be of glacial origin that have been recorded regularly at stations near the summit of Mount Rainier since June 2nd have decreased in number and amplitude over the past week. USGS and PNSN staff continue to monitor the activity. Elsewhere, seismicity and ground deformation at Cascade Range volcanoes have remained at background levels this week.

CASCADE RANGE VOLCANOES
Current Volcano Alert Level: NORMAL
Current Aviation Color Code: GREEN

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

Recent Observations: On June 17, a magnitude 4.2 earthquake on the east flank of the Cascade Range in southern Washington (0723 hr PDT, 2 km depth) showed its trace on many volcano-monitoring seismometers from Mount Baker in northern Washington to Mount Shasta in northern California. A small swarm of earthquakes has been active on the lower west flank of Mount Hood this week. The largest was M 1.6 (June 17, 6 km depth), too small to be felt by people. Earthquake swarms recur at Mount Hood sporadically and are tectonic, not magmatic, in origin; that is, they originate in response to the relentless forces acting across the Earth's crust in the Pacific Northwest. Elsewhere, seismic activity and ground deformation at Cascade Range volcanoes have remained at background levels this week.

CASCADE RANGE VOLCANOES
Current Volcano Alert Level: NORMAL
Current Aviation Color Code: GREEN

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

Recent Observations: On June 21, a magnitude 1.9 earthquake was generated by normal faulting at Mount Rainier, but such events are not unusual and indicate no change in volcanic activity. Elsewhere, seismic activity and ground deformation at Cascade Range volcanoes remained at background levels this week. Crews took advantage of long-awaited fine weather to perform reconnaissance and equipment maintenance missions.