Cascade Range Current Updates
March 2009

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: Volcano seismicity has remained at background levels throughout the 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: A series of small earthquake swarms occurred Tuesday through Thursday beneath the south flank of Lassen Peak. The earthquakes were centered at ~5 km depth, with the largest quake having a magnitude of 2.2. Such earthquake swarms are not unusual in this area. For more details, see:
http://volcanoes.usgs.gov/activity/archiveupdate.php?noticeid=4027

Activity at all other Cascade volcanoes remains at background levels.


CASCADES VOLCANO OBSERVATORY WEEKLY UPDATE
Friday, March 20, 2009 08:16 PDT (Friday, March 20, 2009 15:16 UTC)

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: A minor swarm of earthquakes occurred at Lassen volcano Tuesday and Wednesday, centered several kilometers south of the volcano's summit at about 4 km depth. The largest quake had a magnitude of about 2.0. Slightly smaller swarms at Lassen occurred last July and October, and typically occur once or twice a year. They are thought to be related to hydrothermal activity rather than magma movement. Activity at all other Cascade volcanoes remains at background levels.

LASSEN VOLCANIC CENTER VOLCANO (CAVW#1203-08-)
40.49°N 121.51°W, Summit Elevation 10456 ft (3187 m)
Volcano Alert Level: NORMAL
Aviation Color Code: GREEN

Information Statement for the recent March 17-19, 2009, Lassen Peak swarm activity

A series of small earthquake swarms have occurred beneath the south flank of Lassen Peak in Lassen Volcanic National Park over the last three days. This activity began at 3:00 AM (PDT) on March 17 and persisted through 8:16 AM on the 19th. Episodic swarm activity on the 17th through 4:10 AM on the18th included some 48 earthquakes large enough to be located, the three largest of which had magnitudes of M=2.1, 2.0, and 2.2. Activity resumed at 6:57 AM on the 19th producing 26 earthquakes by 8:19 AM, the largest of which was a M=1.9. These earthquakes are centered at a depth of roughly 5 km beneath the surface and, in map view, form an elongated pattern extending from the vicinity of Eagle Peak on southwest flank of Lassen Peak to the vicinity of Diamond Peak 3 km further to the south-southwest.

Earthquake swarms are not unusual in this area. This most recent activity was preceded by a swarm of 12 earthquakes on February 13-14 that included a M=1.8 event. Earlier activity in this same area over the last five years includes swarms on February 15-16, 2005 (14 events including a M=2.3 earthquake), February 21 2006 (13 events with a M=2.2 earthquake), January 18-19, 2007 (29 events with a M=1.9 earthquake), and September 7-8, 2008 (41 events with a M=2.3 earthquake). This swarm activity over the past 3 days appears to be within the norm of earthquake activity detected in the Lassen area since the modern seismic network was installed in 1980. The USGS will continue to monitor the situation closely.

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: Activity at all Cascade volcanoes remained at background levels. Field crews were at Mount St. Helens on Thursday, 12 March, to conduct maintenance on remotely-operated cameras and acoustic flow monitors, and to retrieve spiders and a tiltmeter for maintenance prior to future redeployment.

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: Activity at all Cascade volcanoes remained at background levels. A few tiny earthquakes were detected at Mount St. Helens and Mount Shasta.