Lake County Record-Bee - News

 

 

 

 

 

 

May 12, 2004
Lake County, CA

  

 

 

 

 

 

 

 

 

 

Group debates cause of increasing temblors

By John Lindblom - Record-Bee staff

LAKEPORT

Time will tell.

That was the consensus of seismological experts who met Monday in the Lake County Board of Supervisors chamber regarding increased earthquakes or, "events" as they call them in the Anderson Springs area with magnitudes of 3.0 and higher.

The increase was brought to the attention of the Seismic Monitoring Advisory Committee by Jeff Gospe, president of the Anderson Springs Community Alliance.

Gospe believes that temblors of higher magnitude could be increasing along with a marked increase in those in the 1.0 magnitude area, which result from wastewater being injected near the geysers by Calpine.

"You had three magnitude 4 earthquakes within about 20 to 25 years. Then, this past year you have had three magnitude 4s within 10 months of each other, so something's changing," said Gospe.

"Most 3.0s occurred in the late '80s and early '90s, then decreased," Gospe added. "Then injections started and 3s began to increase again."

Gospe used a well-prepared document that noted 36 quakes of 3.0 magnitude in 2002 and 41 in 2003, and projected 36 in the 3.0 or higher range for 2004.

"Personally, I think the 3s and 4s will continue to increase," Gospe said, providing numerous graphs that showed a steady and sometimes dramatic rise in quakes at all levels since 1998, the year wastewater was first injected at the geysers.

Bill Smith of the California Power Agency (CPA) challenged Gospe's projections.

Others in attendance were conservative.

"Three 4s? I don't know. That's such a small number and not enough evidence. We will probably know in about five years if it's a trend," said David Oppenheimer, a U.S. Geological Service researcher, who with Ernie Major of Lawrence Berkeley National Laboratory made the connection between injection of wastewater and the constant earthquakes in the Anderson Spring area.

"You see a lot of smaller quakes because of injections," Oppenheimer added. "That doesn't mean you're going to see a lot of big quakes."

Charles Watson, an earthquake expert for Seismo-Watch, added: "Statistics with small numbers are dangerous. You can't really make a statement on three (4.0 quakes). If the trend continues this way, I think it would be demonstrative to say that it is the case: The geysers are generating more earthquakes."

Mitch Stark, Calpine's resource manager, who was present for the meeting, noted that it was "unusual that last year we had these three (4.0 quakes), but it's not enough to say that there's really a change in the pattern."

Stark refused to link the higher-velocity earthquakes with the millions of gallons of wastewater going into the ground at the geysers.

"None of those had anything to do with injections. They're far from injection wells and don't really relate," he said. "Two of them (in May and August) occurred before water started flowing from Santa Rosa."

Stark further insisted that the number of earthquakes with magnitude of 3.0 has been flat for years. "We average about 17 a year and that hasn't changed since 1984," he said.

Oppenheimer said the quakes of 1.0 magnitude many of them unfelt are definitely increasing, but was reluctant to connect them with those of greater magnitude.

"I don't think it works that way because these are not normal, they're manmade," he said.


2004 Record-Bee.com