USGS/Cascades Volcano Observatory, Vancouver, Washington
Mount St. Helens, Washington -
Summary of Mount St. Helens Volcanic Activity, July 1998
The following information is provided by the U.S. Geological
Survey's Cascades Volcano Observatory and by the
University of Washington's Geophysics Program.
The U.S. Geological Survey and University of Washington monitor
earthquakes and other activity at Mount St. Helens as part of the
USGS Volcano Hazards Program.
In the month of June, 318 well-located (quality BB or better),
high-frequency earthquakes occurred beneath
Mount St. Helens, with the largest earthquake having a magnitude of 1.8.
In July 445 earthquakes, including two
of magnitude 2.0 were located in the same area. Near the end of July,
activity decreased. In the month of August,
only 48 earthquakes were located in the area from Aug. 1-12.
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Mount St. Helens Seismicity - Time vs. Depth
Graph showing relationship between time and depth of earthquakes beneath
Mount St. Helens from
August 1997 to July 1998.
In this graph, 0 depth is referenced to 1.5 km (about 1
mile) below the current summit of Mount St. Helens (8,363 feet above sea
level).
For More Information:
Link to:
Mount St. Helens Seismicity Information
-- Link courtesy
University of Washington Geophysics Program
Return to:
[Mount St. Helens Menu] ...
[Mount St. Helens Current Activity Menu]
[Mount St. Helens Monitoring Menu]
URL for CVO HomePage is:
<http://vulcan.wr.usgs.gov/home.html>
URL for this page is:
<http://vulcan.wr.usgs.gov/Volcanoes/MSH/CurrentActivity/1998/summary_jul98.html>
If you have questions or comments please contact:
<GS-CVO-WEB@usgs.gov>
08/12/98, Lyn Topinka
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