Many clean energy advocates include geothermal power—energy generated from the copious amounts of heat beneath the Earth’s surface—in their recipes for a clean energy future. Manifestations of the awesome power swirling below the earth’s crust are probably familiar: the relaxing soak provided by natural hot springs and the apocalyptic fury of a volcanic eruption both originate from below.

Geothermal energy production is far cleaner than burning coal, oil, or natural gas, a very good thing indeed. And unlike wind or solar power, the Earth’s heat is always on. But drilling (literally) into the Earth’s inherent energy potential isn’t without risks. A series of recent earthquakes near operating geothermal projects has stoked concerns that the method, improperly sited, could yield a catastrophe.

Most recently, residents of the German town of Landau In Der Pfalz were shaken by a 2.7 magnitude temblor. Though injuries and structural damage to the city didn’t occur, the quake cast a shadow over the local geothermal project, which seismologists concluded was responsible for the shake-up (officials from Geox, the project owner, partially disputed those claims).

Basel, Switzerland was rocked by a 3.7 magnitude quake in 2006, courtesy a local geothermal project that was digging miles below the topsoil. Hardened earthquake veterans may guffaw at the miniature magnitudes of these quakes, but this New York Times article notes that "triggered quakes" tend to occur closer to the Earth’s surface and produce experiences more severe than the seismic ratings imply.

Cut to California, where a company called AltaRock Energy is implementing a project similar to the one in Basel, just shy of 100 miles north of San Francisco. High hopes for domestic geothermal are pegged on the project, which received more than $6 million in funding from the Department of Energy. But recent technical problems and rising concern over the possibility of triggered quakes in an area with more faults than a politician have held progress up. A triggered earthquake in northern California is worrisome, to say the least.

The potential of geothermal is real. But so are the tensions between the safety of local communities and the urgent need for clean power. Will the fear of a triggered earthquake, especially in a region like the Bay Area, all-too-familiar with the destruction earthquakes can produce, ultimately outweigh the desire to tap a clean source of energy?