Mount St. helens Unexpectedly Explodes

Mount St.Helens Unexpectedly Explodes

by Mitch Battros - ECTV
At 5:25 PM (Pacific) Mount St. Helens erupted spewing ash and rock six miles into the sky. Airlines have been ordered to stay clear of a 20 mile radius. The ash explosion happened around 5:25 p.m., about an hour after a 2.0 magnitude quake rumbled on the east side of the mountain, said Bill Steele, coordinator of the Pacific Northwest Seismograph Network at the University of Washington.

Steele said he did not believe the explosion had increased the risk of a significant eruption and noted that recent flights over the volcano's crater did not reveal high levels of gases.

Steele said the ash burst may have been triggered by partial collapse of a lava dome in the crater, which has been growing steadily over the last several months. "Until we get a better view in the crater we won't know," Steele said.

Steele said there had been no increase in quake activity before the explosion. "The seismicity had been continuing just as it had been," she said.

On May 18, 1980, the volcano 100 miles south of Seattle blew its top, killing 57 people and covered the region with gritty ash.

***Watch for a follow-up report late tonight or early morning.

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Every Tuesday and Thursday from 9 PM to 10 PM (Pacific). Go to the ECTV home page and click on "Listen Live" which sits at the top right of the page.

Tuesday March 8th – Bill Steele – Seismology Lab Coordinator for the Pacific Northwest Seismograph Network (PNSN) at the University of Washington Department of Earth and Space Sciences. Mr. Steele directs the educational outreach program for the network, and serves as Public Information Officer (PIO) for both the PNSN and for many USGS earthquake-related research activities in the Pacific Northwest. Directing the expansion of the PNSN outreach program, he has worked extensively with private and public sector organizations to better address their information needs and to build coalitions to meet mutual concerns. PNSN Website: http://www.geophys.washington.edu/SEIS/PNSN/

Mitch Battros

Producer - Earth Changes TV

http://www.earthchangestv.com
==========================================
SEE:
http://vulcan.wr.usgs.gov/Volcanoes/Cascades/CurrentActivity/current_updates.html

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

Mount St. Helens Information Statement,
Tuesday, March 8, 2005, 6:00 P.M. PST

A small explosive event at Mount St. Helens volcano began at approximately 5:25 p.m. PST. Pilot reports indicate that the resulting steam-and-ash plume reached an altitude of about 36,000 feet above sea level within a few minutes and drifted downwind to the east-northeast. The principal event lasted about 30 minutes with intensity gradually declining throughout. The USGS Cascades Volcano Observatory lost radio signals from three monitoring stations in the crater soon after the event started. The cause of the outage won’t be known until scientists can visit the crater tomorrow to assess the situation, weather permitting. The event followed a few hours of slightly increased earthquake activity that was noted but not interpreted as precursory activity. There were no other indications of an imminent change in activity.

The current hazard assessment for the ongoing eruption mentions the possibility of such events occurring without warning, and the assessment remains unchanged. The eruption could intensify suddenly or with little warning and produce explosions that cause hazardous conditions within several miles of the crater and farther downwind. Small lahars could suddenly descend the Toutle River if triggered by heavy rain or by interaction of hot rocks with snow and ice. These lahars pose a negligible hazard below the Sediment Retention Structure (SRS) but could pose a hazard along the river channel upstream.

Tuesday, March 8, 2005 8:45 a.m. PST (1645 UTC)

MOUNT ST. HELENS UPDATE

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

Growth of the new lava dome inside the crater of Mount St. Helens continues, accompanied by low rates of seismicity, low emissions of steam and volcanic gases, and minor production of ash. During such eruptions, episodic changes in the level of activity can occur over days to months. The eruption could also intensify suddenly or with little warning and produce explosions that cause hazardous conditions within several miles of the crater and farther downwind. Small lahars could suddenly descend the Toutle River if triggered by heavy rain or by interaction of hot rocks with snow and ice. These lahars pose a negligible hazard below the Sediment Retention Structure (SRS) but could pose a hazard along the river channel upstream.

Potential ash hazards: Wind forecasts from the National Oceanic and Atmospheric Administration (NOAA), coupled with eruption models, show that any ash clouds that rise above the crater rim today would drift eastward early in the day and northeastward later.

Potential ash hazards to aviation: Under current eruptive conditions, any ash clouds produced are unlikely to exceed 15,000 feet in altitude. Ashfall from such events rarely reaches more than 20 miles downwind. If the lava dome continues to grow over the next several months, it will become able to produce larger ash clouds that reach higher altitudes and extend farther downwind.

Recent observations: The volcano is clear this morning and absent a steam plume. However, crews will not be going to the field until later in the week, weather permitting. When they do go out, they plan to conduct visual observations, thermal imaging, equipment maintenance, and retrieve a GPS package. Small earthquakes continue to occur at a pace similar to that of the past several weeks. No large quakes have been recorded since Saturday.

For additional information, background, images, and other graphics: http://vulcan.wr.usgs.gov/Volcanoes/MSH/Eruption04/

For seismic information: http://www.pnsn.org/HELENS/welcome.html

For a definition of alert levels: http://vulcan.wr.usgs.gov/Volcanoes/Cascades/CurrentActivity/volcano_warning_scheme.html

For a webcam view of the volcano: http://www.fs.fed.us/gpnf/volcanocams/msh/

Telephone recordings with the latest update on Mount St. Helens and phone contacts for additional information can be heard by calling:

Media (360) 891-5180

General public (360) 891-5202

OTHER CASCADE VOLCANOES

All other volcanoes in the Cascade Range are all at normal levels of background seismicity. These 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.