Subsurface carbon sequestration—storing carbon in rocks deep underground—offers a partial solution for removing carbon from the atmosphere.
Subsurface carbon sequestration—storing carbon in rocks deep underground—offers a partial solution for removing carbon from the atmosphere. Used alongside emissions reductions, geologic carbon sequestration could help mitigate anthropogenic climate change. But like other underground operations, it comes with risks—including earthquakes.
Geophysicists are still working to understand what can trigger human-induced earthquakes, which have been documented since the 1960s. A new study, published in Geology on Thursday, explores why part of a heavily produced oilfield in the U.S. has earthquakes, and part of it doesn’t. For the first time, the authors demonstrate that the influence of past oil drilling changes stresses on faults in such a way that injecting fluids is less likely to induce, or trigger, earthquakes today.
The study focuses on the Delaware Basin, an oil- and gas-producing field spanning the border between West Texas and New Mexico. Drilling there has taken place since at least the 1970s, with over 10,000 active individual wells dotting the region. There, Stanford geophysicists No’am Dvory and Mark Zoback noticed an interesting pattern in seismic activity. Recent shallow earthquakes were mostly located in the southern half of the basin, while the northern half is seismically quiet, despite shallow wastewater injection occurring across the basin.
“The compelling question, then, is why are all the shallow earthquakes limited to one area and not more widespread?” Zoback says.
Read more at Geological Society of America
