[pct-l] Cascades Volcano Observatory

[ATnavi@aol.com (ATnavi@aol.com)]

PCT hikers --
There's a great resource at http://vulcan.wr.usgs.gov/home.html to keep you 
up to date on what the seismologists and geologists are finding out about the 
Cascades region. They've been monitoring these mountains for many years -- 
especially Rainier. Remember, you're out there hiking amid a string of 
volcanoes! They had this comforting observation on yesterday's quake:

"A large earthquake (magnitude 6.8 centered about 11 miles northeast of 
Olympia at a depth of about 33 miles occurred this morning at 10:54 PST. 
There are reports of widespread damage in the Seattle, Tacoma, and Olympia 
areas. The earthquake signal saturated the seismic stations at Mount St. 
Helens for several minutes and detectable ground vibrations continued for 
tens of minutes. Observers from the U.S. Forest Service and Weyerhaeuser 
Corporation reported that there were no new large rock or snow avalanches 
from the crater walls or flanks of the volcano. The gage that measures the 
level of Castle Lake indicated a small wave (a few inches high) sloshed 
across the lake. Local seismicity remains unchanged since the main shock.

No changes in local seismicity have been observed at Mount Rainier either 
since the main shock. The Puyallup valley lahar-detection system responded to 
the main shock, but since the parameters necessary for lahar detection were 
not met, the system returned to its normal mode. This is the first test of 
the system's response to a large-magnitude local earthquake and it responded 
as designed. 

Volcanoes in the Cascade Range are all at normal levels of background 
seismicity. These include Mount Baker, Glacier Peak, Mount Rainier, Mount 
Adams, and Mount St. Helens 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."

Cheers, Navigator