Earthquake activity beneath Mount St. Helens remained at a low level during July 1997. There were 24 well-located earthquakes during July. The largest was a M 1.2, but the vast majority were less than M 0.0. Although this was the largest number of earthquakes since December 1995, it still is well within the range of what would be considered normal.

Mount St. Helens Seismicity - Map and Cross-Section
Cross-sectional view showing the locations of earthquakes beneath Mount St. Helens during July 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).

Mount St. Helens Seismicity - Time vs. Depth
Graph showing relationship between time and depth of earthquakes beneath Mount St. Helens from June 30, 1996 to July 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).

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. Information updates will be posted here during the first week of each month, or more often if conditions warrant. Additional information is available from the University of Washington Geophysics Program at the following URL:

http://www.geophys.washington.edu/SEIS/PNSN/HELENS