Fears of disaster after eight quakes in 2 weeksgreenspun.com : LUSENET : Grassroots Information Coordination Center (GICC) : One Thread
Fears of disaster after eight quakes in 2 weeks
By JIM ERICKSON, Scripps Howard News Service
September 09, 2001
TRINIDAD, Colo. - Depending on which rumor you believe, this scenic border town is about to be washed away by an epic flood or leveled by the Big One.
There's no evidence to support either claim, but that doesn't stop the rumormongers in this town rattled by eight magnitude 3.4 to 4.5 earthquakes since Aug. 28.
Some residents are convinced that the earthen dam that holds back Trinidad Lake, three miles upstream from Trinidad, is about to burst, sweeping away the town. Others say the quakes are Mother Nature's payback for pumping too much natural gas - and that bigger quakes may be coming. Since 1995, more than 1,300 permits to drill for methane gas have been issued here.
"I'll bet nine out of 10 people here think that it's the gas companies sucking the stuff out of the ground that's causing it," said filmmaker Mark Hutto, co-owner of HBL films in Segundo, a few miles west of Trinidad.
Though the U.S. Geological Survey's national seismic network has recorded eight quakes in the area since Aug. 28, Hutto said he's felt at least 25 during that time. He owns a century-old brick house and an adobe store in Segundo; walls in both structures cracked during the magnitude 4.5 quake Wednesday, he said.
Magnitude 2.5 to 3 quakes are the smallest generally felt by people. Magnitude 4 quakes can cause moderate damage. There have been no injuries in the tremors. To pinpoint the source of the quakes and to help determine why they're happening, the Geological Survey is installing seven portable digital seismographs in the area.
There are no mapped faults in the Trinidad area. Before the current quakes, the last tremors recorded there by the U.S. National Seismic Network occurred in 1973, said Geological Survey geophysicist Mark Meremonte.
"There was no activity for 28 years. Then, all of a sudden, there is a flurry of activity, a swarm of activity," Meremonte said. "For some place along the San Andreas Fault that may not be unusual, but for this area it's unusual."
Preliminary analysis of data from the quakes suggests there may be a previously unknown fault west-southwest of Trinidad. Early data suggest it may by a "normal" fault, a type of fracture produced by tensional stress. There is no indication that the recent quakes are precursors to a larger one, Geological Survey researchers say.
(Jim Erickson writes for the Rocky Mountain News in Denver)
-- Swissrose (firstname.lastname@example.org), September 10, 2001