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USGS/Cascades Volcano Observatory, Vancouver, Washington

Mount St. Helens, Washington -
Summary of Mount St. Helens Volcanic Activity, October 1997


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.

There were 42 well-located (quality BB or better) events at MSH in October. Of these, 12 had magnitudes >0.0 (29% of all earthquakes), with the largest a M 1.1. For reference, September had 25 events with M >0.0 (50% of the 50 total earthquakes) and August had 7 events with M >0.0 (18% of the 38 total eathquakes).

[Map,11K,GIF]
Mount St. Helens Seismicity - Map and Cross-Section
Cross-sectional view showing the locations of earthquakes beneath Mount St. Helens during October 1997. The cross-section represents a vertical slice of the crust downward from line A-A' in the map view. The earthquakes occurred in and around the magma conduit system that leads from the magma reservoir to the dome. 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).

[Map,9K,GIF]
Mount St. Helens Seismicity - Time vs. Depth
Graph showing relationship between time and depth of earthquakes beneath Mount St. Helens from November 1, 1996 to October 31, 1997. 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



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11/07/97, Lyn Topinka