Nature:
Three papers published in
Science this week link the injection of fluids
underground—during natural-gas extraction,
geothermal-energy production, and other activities—with
increased seismic activity. According to the studies, the
number of US earthquakes of magnitude 3.0 or higher has
increased almost 10-fold in the past decade, and at least half
of those of magnitude 4.5 or higher have occurred near
injection-well sites. The
study
by William Ellsworth of the US Geological Survey indirectly
links the increase in the number of earthquakes to the practice
of hydraulic fracturing, or fracking, by claiming it is the
wastewater from the process that is causing the problem. The
study
by Nicholas van der Elst of Columbia University and colleagues
suggests that some well sites are more sensitive than others
and that earthquakes there can be triggered by large quakes
that occur in other parts of the world. The third
study,
by Emily Brodsky and Lia Lajoie of the University of
California, Santa Cruz, acknowledges that increased seismicity
accompanies geothermal power production, although the rate at
which earthquakes are induced cannot yet be forecast.
