Cascade Range Current Updates
November 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: As is common in the fall, high winds and rainstorms continue to generate substantial noise at times on seismic records and create minor telemetry problems as antennas accumulate ice. A small earthquake swarm occurred starting at around 2 PM on November 3 at Lassen Peak, with one M2.5 quake and a couple dozen smaller events. Such events are common at Lassen and appear related to regional tectonic stresses.

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. Mount St. Helens has been at Volcano Alert Level NORMAL (Aviation Color Code GREEN) since July 10, 2008.

Recent Observations: Monitoring data, chiefly volcano seismicity, show only background levels of activity at Cascade Range volcanoes during the week.

Lassen Volcanic Center Volcano
40°29'31" N 121°30'29" W, Summit Elevation 10456 ft (3187 m)
Current Volcano Alert Level: NORMAL
Current Aviation Color Code: GREEN

Information Statement for the November 2-10, 2009, Lassen Peak swarm activity

A series of small earthquake swarms beneath the southwest flank of Lassen Peak in Lassen Volcanic National Park that began in the late evening on November 2 continued with sporadic activity diminishing through the 16th. The activity was most intense on the November 3rd with the largest earthquake in the sequence a magnitude M=2.5 event at 1:54 PM (PDT) on the 3rd. These earthquakes are centered some 3 km (2 miles)southwest of the summit of Lassen Peak between Eagle Peak and Mount Diller at a depth of roughly 5 km (3 miles) beneath the surface.

Earthquake swarms are not unusual in this area. Earlier activity in this same area over the last five years includes swarms on March 2009, 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 most recent swarm activity 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.

Lassen Volcanic Center Volcano
40°29'31" N 121°30'29" W, Summit Elevation 10456 ft (3187 m)
Current Volcano Alert Level: NORMAL
Current Aviation Color Code: GREEN

Information Statement for the November 2-16, 2009, Lassen Peak swarm activity

A series of small earthquake swarms beneath the southwest flank of Lassen Peak in Lassen Volcanic National Park that began in the late evening on November 2 continued with sporadic activity diminishing through the 16th. The activity was most intense on the November 3rd with the largest earthquake in the sequence a magnitude M=2.5 event at 1:54 PM (PDT) on the 3rd. These earthquakes are centered some 3 km (2 miles)southwest of the summit of Lassen Peak between Eagle Peak and Mount Diller at a depth of roughly 5 km (3 miles) beneath the surface.

Earthquake swarms are not unusual in this area. Earlier activity in this same area over the last five years includes swarms on March 2009, 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 most recent swarm activity 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.

This statement corrects an error in the first line of the release yesterday (11/17/2009)

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. Mount St. Helens has been at Volcano Alert Level NORMAL (Aviation Color Code GREEN) since July 10, 2008.

Recent Observations: Data from monitoring equipment have indicated only background levels of activity at Cascade Range volcanoes during the week. A series of strong Pacific storms has pounded the Cascades Range this week, however, sometimes producing noisy seismometer outputs unrelated to volcanic or tectonic activity. No earthquakes have been recorded at Lassen Peak volcano since abatement of the November 2-16 swarm.

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. Mount St. Helens has been at Volcano Alert Level NORMAL (Aviation Color Code GREEN) since July 10, 2008.

Recent Observations: Cascade Range volcano seismicity and deformation have remained at background levels during the past week.