Mount St. Helens Update, October 9, 2004

International Glaciospeleological Survey

Mount St. Helens Update, October 9, 2004

U.S. Geological Survey, Vancouver, Washington
University of Washington, Pacific Northwest Seismograph Network, Seattle, Washington

Mount St. Helens Update, October 9, 2004, 7:00 a.m. PDT Current status is Volcano Advisory (Alert Level 2); aviation color code ORANGE.

Seismic activity leveled off overnight after rising gradually for most of yesterday (10/08), with earthquakes up to magnitude 2.4 presently occurring at a rate of about 1 every two minutes. No visual observations of the crater and dome were possible yesterday due to low clouds and rain. Acoustic Flow Measurement (AFM) data showed no evidence of lahars occurring overnight. Field work yesterday was limited to observations of river flows and installation of a satellite dish near Coldwater Visitor Center for telemetry of seismic, GPS, and other data. Measurements from recent photographs and LIDAR (an acronym for LIght Detection And Ranging) show that, as of 10/07, the intensely deformed and uplifted area on the south side of the 1980-86 lava dome is about 1300 feet (N-S) by 1600 feet (E-W) with a maximum uplift of about 300-400 feet.

As a result of the intense unrest of the past 15 days, we infer that magma is at a very shallow level. During times of unrest, Mount St. Helens and similar volcanoes elsewhere typically go through episodic changes in level of unrest over periods of days to weeks, or even months. Such changes are in part driven by variations in the rate of magma movement. We expect fluctuations in the level of unrest to continue during coming days. Escalation in the degree of unrest and perhaps an eruption could occur suddenly or with very little warning. There may be little time to raise the alert level before a hazardous event occurs. Therefore, we continue to monitor the situation closely and will issue additional updates and changes in alert level as warranted.

Wind forecasts from the National Oceanic and Atmospheric Administration (NOAA), combined with eruption models, show that winds in the early morning will remain westerly and any ash clouds will drift east-northeastwards. Today’s press conference will be held at the Headquarters office of the Gifford Pinchot National Forest at 10:30 a.m.

U.S. Geological Survey, Vancouver, Washington
University of Washington, Pacific Northwest Seismograph Network, Seattle, Washington

Mount St. Helens Update, October 9, 2004, 5:30 p.m, PDT

Current status is Volcano Advisory (Alert Level 2); aviation color code ORANGE

Seismic activity has remained at a moderate, but variable rate. Currently earthquakes up to magnitude 2 are occurring at a rate of about 1 every two to three minutes minutes. No visual observations of the crater, the 1980-86 lava dome, or the intensely deforming and uplifting area on the south side of the dome were possible today due to low clouds. No scientists worked in the field today.

Additional analysis of lidar and photographs of the intensely uplifting area on the south side of the lava dome suggests that the total volume change represented by the deformation between late September and October 6 is about 16 million cubic meters (21 million cubic yards). The average rate of change is about 2 million cubic meters per day (2.6 million cubic yards per day). If this figure represents the rate of intrusion of magma into shallow levels of the dome and(or) underlying crater floor, it is an intrusion rate about twice that measured during dome-building eruptions at Mount St. Helens in the 1980s.

As a result of the intense unrest of the past 11 days, we infer that magma is at a very shallow level. During times of unrest, Mount St. Helens and similar volcanoes elsewhere typically go through episodic changes in level of unrest over periods of days to weeks, or even months. Such changes are in part driven by variations in the rate of magma movement. We expect fluctuations in the level of unrest to continue during coming days. Escalation in the degree of unrest and perhaps an eruption could occur suddenly or with very little warning. There may be little time to raise the alert level before a hazardous event occurs. Therefore, we continue to monitor the situation closely and will issue additional updates and changes in alert level as warranted.

Wind forecasts from the National Oceanic and Atmospheric Administration (NOAA), combined with eruption models, show winds early this evening will remain westerly becoming northwesterly later. Any ash clouds will drift eastward (tonight) and southeastward (early tomorrow morning).

Tomorrow’s media briefing will be held at the Headquarters of the Gifford Pinchot National Forest at 10:30 a.m.


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