Deep Geothermal Drilling Sparks Earthquake Fear in San Francisco Area

But shallow geo-exchange drilling may actually prevent damage from earthquakes

San Francisco area residents are no stranger to earthquakes. Built near fault lines, the city is susceptible to the earth's natural shifts. A new energy project, however, has sparked worry that the city and surrounding area may soon fall prey to a man-made earthquake, caused by geothermal drilling.

Geothermal energy harvests the heat in the earth's bedrock and uses it as fuel. It has huge potential as a clean energy source and, unlike solar or wind power, geothermal energy is always present. The problem, however, is that the drilling used to access geothermal heat has been linked to earthquakes. A previous project in Basel, Switzerland, was shut down after Swiss government seismologists determined that it was the cause of an earthquake that rocked the city in December of 2006. Officials also believe the project to be the cause of several smaller quakes that persisted for months after the project was terminated.

AltaRock Energy, the startup doing the drilling in the San Francisco area, failed to mention the Basel project's connection to earthquakes in its seismic impact report, claiming that it was unsure the project had indeed been the cause of the quake. AltaRock also claims that it chose its project location because a history of smaller quakes, caused by less invasive energy projects in the area, assures the company that the risks are limited. Company officials maintain that it can drill safely, avoiding large fault lines.

With the push for sustainable energy sources and less reliance on fossil fuels, geothermal energy is a ray of hope for many, but for many of those living near geothermal drilling projects, that hope is tinged with fear.

The Other Side of the Coin

Though the hot rock technology (which involves drilling two to three miles below the earth's surface) used by some companies has sparked fear of earthquakes, it would be a mistake to assume that all drilling is a potential cause of seismic problems. This is simply not the case.

Shallow geo-exchange drilling is a safe method of drilling that has been used for decades around the world for thousands of geothermal, water well and foundation drilling projects. While hot rock technology harnesses heat from the earth's core (thousands of feet deep), geo-exchange systems use the heat stored in the earth's crust at depths of only a few hundred feet.

For instance, the the RigKits LLC K40 drilling unit shown at right has been used for earthquake protection purposes. It is capable of capable of drilling foundation and geo-exchange bores and can actually serve to prevent earthquake damage to buildings.

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