All,
Saw the below on the web.
-- Will
 
 
MAMMOTH LAKES, MONO COUNTY  
Popular recreation spot has grown hotter  
Swimming areas cordoned off  
- David Perlman, Chronicle Science Editor 
Wednesday, June 28, 2006  
 
 
The sudden appearance of spouting geysers and bubbling hot springs in the middle of a shallow river near the High Sierra resort town of Mammoth Lakes (Mono County) has caused Inyo National Forest officials to close the area and ban swimming there.  
 
Scientists said Tuesday there are no signs of increased seismic activity in the region that lies within the ancient crater of a long-dormant volcano, so the geysers and bubbling springs in the river known as Hot Creek is probably the result of heavy spring runoff from winter's snows.  
 
An area some 200 yards around the creek has been fenced off since June 6, said Kimberly Ferguson, a Forest Service technician at the Hot Creek Visitors Center.  
 
The Hot Creek Geologic Site, about 7 miles southeast of town, is a popular recreation spot. The center of the 20-foot-wide Hot Creek normally runs pleasantly warm -- and sometimes hot -- year-round, while the rest of the water is cold. Although it's not deep enough for serious swimming, it is noted as a nice place to bask.  
 
But the restless stream flows through the famed Long Valley Caldera, a vast, nearly circular crater that marks all that's left of a giant volcano that blew its top some 760,000 years ago and covered the surrounding terrain with intensely hot ash before a second eruption buried thousands of miles of western America in more ash.  
 
Early this month, forest rangers noticed the new geysers and steam welling up from new hot springs along the margins of Hot Creek and quickly fenced off the area while they notified scientists at the U.S. Geological Survey in Menlo Park.  
 
David P. Hill, a geophysicist at the USGS who is the leading expert on the Caldera's volcanism and seismic activity, promptly began surveying the area for signs of imminent earthquake danger and tentatively concluded Tuesday that there is none.  
 
At the USGS offices, geophysicist Randall A. White agreed, saying the ground throughout the entire area was unusually quiet.  
 
Only three tiny earthquakes registered on the facility's seismic monitors Monday, White said, with none larger than magnitude 2. In the past, he said, as many as 1,000 small earthquakes have registered there in a month, but almost all have been smaller than magnitude 3.  
 
"There's certainly no unusual seismic activity up there right now," White said.  
 
Hill and a team of USGS scientists who make up the Long Valley Observatory described the Hot Creek situation at the spot where the public usually swims in a report released Tuesday.  
 
The appearance of fresh hot springs, geysers and bubbling mud pots is most probably being caused by unusually heavy spring runoff from this past winter's snows seeping into the ground and encountering heat rising from the volcano's magma many miles deep within the caldera floor, the team tentatively concluded.  
 
Snowmelt, the team believes, probably infiltrates down to rising hot magma and can reach up to 428 degrees Fahrenheit before cooling to about 199 degrees at the Hot Creek Gorge. It's the meeting of cold water and hot rock that creates the geysers and the bubbling springs and mud pots in the creek, the scientists said.  
 
"The recent upswing in hydrothermal activity ... does not appear to be of tectonic or volcanic origin," Hill and his team said in their consensus report.  
 
The Hot Creek region is crowded with visitors right now, but they seem more curious than worried about the sudden eruption of hot water, said Ferguson, the Forest Service technician. In fact, she said, the region is becoming less restless.  
 
"Actually, the geysers that were spouting about 7 feet high a few weeks ago are now dying out, and the springs aren't running as fast as they were doing," she said. 
