Cascade Range Current Update

Volcanoes in the Cascade Range are all at normal levels of background seismicity except for Mount St. Helens. See Mount St. Helens update below.

Other volcanoes 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.

Mount St. Helens Update
September 30, 2004 5:45 P.M., PDT

The alert remains at a Volcano Advisory. Today the seismic energy level remained elevated with a rate of 3-4 events per minute and included events as large as magnitude 3.3. All earthquake locations are still shallow and in or below the lava dome. Data from a single GPS instrument on the east side of the lava dome suggest that the site moved a few inches northward Monday and Tuesday, but has since been stable. Such movement is not surprising in light of the high seismicity levels. A USGS field crew collected additional data from GPS equipment deployed to monitor any ground movement on the lava dome, crater floor, or lower slopes of the volcano. A gas flight today again failed to detect any significant volcanic gas, as was the case on Monday and Wednesday. Tomorrow, field crews will use a thermal- imaging device (FLIR) to look for thermal anomalies on the dome, and will install additional seismometers on the flanks of the volcano to enhance our ability to detect earthquakes. A press conference will be held Friday at CVO at 9:30 am to update the media.

The current hazard outlook is unchanged from that outlined in yesterday's Volcano Advisory. Updated wind forecasts from the National Oceanic and Atmospheric Administration coupled with an eruption model indicate that the wind direction are out of the northeast. Therefore any ash clouds produced today will drift southwestward.

Confusion at yesterday’s press briefing at CVO regarding Alert Levels resulted in numerous calls to emergency management agencies from the public about which is the correct level. We are at Alert Level Two—Volcano Advisory. Explanation of the alert- level scheme can be found on the “News and Current Events” webpage below.

Our "News and Current Events" webpage now contains "Quick Links" to the current update, current photos, and the University of Washington Mount St. Helens seismicity information, plus other useful "Background" webpages on Mount St. Helens, including an explanation of the Cascade Range alert-level scheme.



Past Updates

News and Current Events