International Glaciospeleological Survey

U.S. Geological Survey, Vancouver, Washington University of Washington,  Pacific Northwest Seismograph Network, Seattle, Washington Mount St. Helens Update, October 11, 2004, 7:45 a.m, PDT Current status is Volcano Advisory (Alert Level 2); aviation color code  ORANGE Seismicity overnight remained at a low level similar to October 10. Small  earthquakes (about magnitude 1) have continued at a rate of about 1 per 5 to 10  minutes. Viewing conditions were very clear most of October 10, and fresh snow had  fallen to the level of the crater floor north of the dome. A USGS field crew noticed a thin ash deposit on the snow in the crater and just beyond the crater  rim, trending southeast from the active area. A steam plume rose to crater rim level or slightly above all day on October  10, heading to the southeast. USGS field workers described the plume as “lazyâ€�—no gas thrust or notably vigorous convection was observed. The plume was clean, with no noticeable ash or blue/orange haze. The odor of H2S was noted at  the crater breach, but not elsewhere. Helicopter field crews were at work on Sunday October 10. A telemetered  webcam was placed at Sugarbowl and GPS data were downloaded. The thermal imaging crew made an excellent video of the uplifted area of the south crater floor. The western portion of the the uplift was steaming over a large diffuse area. Maximum measured surface temperatures were 200-300 deg. C. The thermal imaging crew judged the uplifted area to have grown since it was last seen on the 7th. No gas observations were made on October 10. Rockfall deposits were not seen on or around the uplifted area, perhaps  indicating a lull in its growth or deformation. As a result of the intense unrest of the past 18 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, oreven 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. The weather forecast for the next several days is favorable for fieldwork and  observations. Wind forecasts from the National Oceanic and Atmospheric Administration (NOAA), combined with eruption models, show winds today will remain north-northwesterly. Any ash clouds will drift south- southeastwardly to  southeastwardly. 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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U.S. Geological Survey, Vancouver, Washington University of Washington,  Pacific Northwest Seismograph Network, Seattle, Washington Mount St. Helens Update, October 11, 2004, 5:30 p.m, PDT Current status is Volcano Advisory (Alert Level 2); aviation color code  ORANGE Seismic activity remained at a low level today. Currently small earthquakes  (maximum about magnitude 1) are occurring 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 during the afternoon. The western part of the uplifting area  appears to be the most actively deforming site and was the source of a brief steam and emission about 16:00 that drifted southeastward. A dusting of ash on new snow in that sector suggests that similar minor ash emissions also occurred  last night. A steam plume originating on the deforming area continues to rise  above the crater rim and drift to the southeast. Scientists also conducted a  gas-sensing flight. Results will be available tomorrow as will results of thermal imaging. As a result of the intense unrest of the past two weeks, 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 this evening will remain northwesterly. Any ash clouds will drift south-southeastwardly to southeastwardly. 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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