Cascade Range Current Updates
October 2008

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, a change assigned 5-6 months after the late January cessation of its 2004-2008 eruption.

Crews were in the field this week at Mount St. Helens to continue winterization and maintenance of monitoring and telemetry sites, and to complete collection of spring-water samples for annual geochemical monitoring. A trip to continuous GPS station WIFC in the Three Sisters replaced a damaged cable that was causing episodic data-transmission drop outs.

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, Mount Shasta, and Lassen Peak in northern California. Mount St. Helens has been at Volcano Alert Level NORMAL (Color Code GREEN) since July 10, 2008, a change assigned 5-6 months after the late January cessation of its 2004-2008 eruption.

Crews were in the field this week at Mount St. Helens replacing/repairing/winterizing various field instrumentation. One party also mapped out the margin of the west arm of Crater Glacier and found that it had advanced 5 to 15 meters along its breadth since July 31, 2008. At Mount Hood, a field crew collected spatial data to use as control for an aerial photograph analysis aimed at assessing the dominant triggering processes and volumes of sediment involved in the generation of debris flows in Elliot Creek in November 2006.

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, Mount Shasta, and Lassen Peak in northern California. Mount St. Helens has been at Volcano Alert Level NORMAL (Color Code GREEN) since July 10, 2008, a change assigned 5-6 months after the late January cessation of its 2004-2008 eruption.

Fieldwork at Mount St. Helens comprised a test installation of a self-healing, self-forming mesh network for monitoring instruments. The goal is to have a robust network of instruments that are interconnected for their radio communications, so that the loss of one or even a few installations does not compromise the ability to transmit data. At the Three Sisters, GPS and seismic stations were winterized. At Crater Lake, four broadband receivers were recovered, following their summer 2008 deployment for a seismic-monitoring experiment.

MOUNT ST. HELENS VOLCANO (CAVW#1201-05-)
46.20°N 122.18°W, Summit Elevation 8363 ft (2549 m)
Volcano Alert Level: NORMAL
Aviation Color Code: GREEN

The 40-month-long lava-dome eruption of Mount St. Helens that began in autumn 2004 ended in late January of this year. Earthquakes, volcanic gas emissions, and ground deformation are all at pre-eruptive background levels. The alert level and aviation color code were reduced to NORMAL/GREEN on July 10, 2008, following five months with no sign of renewed activity.

Even with the end of lava dome growth, some hazards persist. The new lava dome remains hot in places and capable of producing small hot avalanches or minor explosions that could dust areas with ash up to tens of miles downwind. Rock fall from the crater walls can produce clouds of dust that rise above the crater rim, especially during dry, windy days, as has happened in the past. Also, heavy rainfall or rapid snowmelt can send small debris flows onto the Pumice Plain north of the crater.

Recent observations: Volcano seismicity at Mount St. Helens and elsewhere has remained quiet over the past week. Given the onset of wet weather, and snow at higher elevations, this has also been a quiet week for field work in the Cascades. The only significant field activity has been reoccupation of campaign GPS sites in the vicinity of the Three Sisters.