Geophysicists are increasingly certain that expanding production of shale gas is responsible for a spate of minor earthquakes that have upset some communities and prompted authorities in Arkansas, Ohio, Oklahoma, and the U.K. to shut down some natural-gas operations. The question now, say the experts, is whether the underground operations causing the trouble should be scaled back or more closely monitored to minimize future quakes—and whether the relatively small quakes may yet have the potential to trigger truly destructive ones.

At least one shale gas producer is already talking change: U.K.-based Cuadrilla Resources, whose first project set off quakes near Blackpool last year.

Shale gas operations generate microseismicity in two ways. One is through hydraulic fracturing, or "fracking," the underground blasts of water, sand, and chemicals used to release the natural gas trapped within shale deposits. Fracking is how Cuadrilla caused a quake that measured 2.3 on the Richter scale last April, according to an analysis by the firm's geophysical consultants.