© anonymouswhole lot of shaking goin' on
At last, something that fossil fuels and renewable energy exploration have in common: They both may cause earthquakes.

Whole lotta shakin' goin' on

The New York Times reported Wednesday on concerns that a geothermal energy project about to begin near San Francisco could trigger quakes in the seismically active region. Worried residents point out that a similar project in Switzerland was shut down in 2006 after it was blamed for a magnitude 3.4 quake - enough to cause quite a stir in an area not accustomed to temblors.

If all this sounds familiar, recall the hubbub earlier this month when some residents of Cleburne, Texas, blamed natural-gas drilling for causing a series of minor earthquakes in the town. Geophysicists took the concerns seriously enough to deploy seismic sensors around the town - at which point the quakes promptly stopped.

Among those convinced the drilling and the earthquakes are related: Markus Haring, a former oilman and the head of the Swiss geothermal project. After the Wall Street Journal wrote about the Cleburne quakes, Mr. Haring emailed to say there is "not the slightest doubt" that gas production caused the temblors.

Mr. Haring's project actually relies on similar technique to the drilling taking place in Cleburne. Both involve injecting water into the ground to fracture rock formations far beneath the surface. In the case of gas production, the method is used to crack open gas-bearing rock so the gas can flow to the surface. The Swiss project involved injecting water into hot rock underground and then pumping the heated water back up to the surface, where it can be used to generate electricity.

The California project relies on the same basic technology, although executives at AltaRock Energy Inc. say they've improved the method and won't cause serious quakes. Residents aren't so sure - one told the Times the project was "terrifying."

The idea that human activity can cause seismic activity is widely accepted in the scientific community. A 2000 paper in the journal Oilfield Review - published by the oilfield services giant Schlumberger Ltd. - noted that the connection between oil production and earthquakes dates back to at least the 1920s, when geologists in South Texas noted faulting near the Goose Creek oil field.

Human-triggered quakes are usually minor, but not always. A 1967 quake in western India that killed about 200 people was linked to the nearby Koyna Dam.