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USGS/Cascades Volcano Observatory, Vancouver, Washington

Cascade Range Current Update

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

Mount St. Helens Update, October 6, 2004, 7:00 a.m, PDT

Current status is Volcano Alert (Alert Level 3); aviation color code RED

Seismicity overnight has remained at very low levels. After the vigourous steam-and-ash emission of yesterday morning, seismicity dropped with individual events becoming smaller. By about 5 p.m. PDT yesterday, individual events became rare and as of 11:00 p.m., seismicity has been stable at a low level.

Yesterday, field crews continued to harden GPS sites for the approaching winter and retrieved data. The GPS sites on the dome survived the steam-and-ash emission and data are being received and processed at the observatory. The station on the northern flank of the dome, shows a trend of northward displacement totaling 2 cm in the last three days. This is the same sense of movement recorded by the nearby station that was destroyed by the first steam-and-ash emission on 1 October. Data from the other two stations on the dome, which were installed on 4 October are currently being analyzed. Data from GPS instruments on the outer flanks of the volcano show no movement of the outer flanks.

No gas measurements were made yesterday. A seismic crew installed an additional broadband seismometer on the northwest flank of the volcano which will help show a broader range of seismic energy release. With the help of the U.S. Forest Service, field crews installed an antenna mast for a VSAT uplink which will improve our ability to retrieve data from the field.

It began raining t the mountain at about 7:30 p.m. PDT. By about 9:30 p.m. about 0.1 inch of rain had fallen. Overnight, the acoustic flow monitoror (AFM) in the crater indicated that several small debris flows had moved past the site. By midnight, higher flows were recorded at a station on the pumice plain, but none were large enough to trigger an automatic alert. We expect these types of flowage events to recur during intense rainstorms.

Wind forecasts from the National Oceanic and Atmospheric Administration (NOAA), combined with eruption models, show winds this morning are from the west-southwest such that any ash clouds will drift to the east-northeast.

We continue to monitor the situation closely and will issue additional updates and Alert Level changes as warranted.

Press conferences will continue to be held at the Headquarters office of the Gifford Pinchot National Forest. The morning press conference is at 9:30 AM. If activity remains low, we will do a show-and-tell of some of the instruments were are using to monitor the volcano at the press conference.



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10/06/04, Lyn Topinka