Cascade Range Current Update

Volcanoes in the Cascade Range are all at normal levels of background seismicity except for Mount St. Helens. See Mount St. Helens update below.

Other volcanoes include Mount Baker, Glacier Peak, Mount Rainier, and Mount Adams in Washington State; Mount Hood, Mount Jefferson, Three Sisters, Newberry, and Crater Lake, in Oregon; and Medicine Lake, Mount Shasta, and Lassen Peak in northern California.

USGS Cascades Volcano Observatory, the Pacific Northwest Seismograph Network at the University of Washington, and the USGS Northern California Seismic Network and Volcano Hazards Team in Menlo Park, California, monitor the major volcanoes in the Cascade Range of northern California, Oregon, and Washington.

Mount St. Helens Update, October 12, 2004, 7:00 a.m, PDT

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

Seismic activity remained at a low level overnight. Small earthquakes (maximum about magnitude 1) continue to occur at a rate of about 1 per 5 to 10 minutes. Visual observations and thermal imaging of the crater, the 1980-86 lava dome, and the intensely deforming and uplifting area on the south side of the dome were made yesterday afternoon. Thermal imaging of the western part of the uplifting area revealed temperatures of 500 to 600 degrees C on a large pinkish-gray fin of rock and in nearby fumaroles and cracks. These observations are consistent with new lava having reached the surface of the uplift. Additional visual and thermal observations will be made today to further evaluate this interpretation.

A gas-sensing flight yesterday measured fluxes of sulfur dioxide and carbon dioxide that are similar to or slightly smaller than those measured on 7 October. The next gas-sensing flight is scheduled for tomorrow.

Wind forecasts from the National Oceanic and Atmospheric Administration (NOAA), combined with eruption models, show winds this morning will remain northwesterly. Any ash clouds will drift south-southeastwardly to southeastwardly.

As a result of the intense unrest of the past two weeks and yesterday’s observations, we infer that magma is at a very shallow level, and perhaps at the surface. 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 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.

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



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