Fracking and energy exploration connected to earthquakes, say studies
The rivers of water pumped into and out of the ground during the production of natural gas, oil and geothermal energy are causing the Earth to shake more frequently in areas where these industrial activities are soaring, according to a series of studies published today. While the gas extraction process known as hydraulic fracturing (aka "fracking") causes some small quakes, it's the disposal of wastewater following that process — and many others relating to energy production — that lead to the largest tremors.
Within the central and Eastern United States, more than 300 earthquakes of magnitude 3 or greater were recorded from 2010 through 2012, compared to an average rate of 21 earthquakes per year from 1967 to 2000, he noted in a review study on human-induced earthquakes published today.
In southern California, researchers have found a correlation between seismic activity and a geothermal power plant that pumps water out of an underground reservoir to produce steam that spins electricity generating turbines and then returns most of the water back underground.
Most of the earthquakes at the Salton Sea geothermal field are tiny, but there is "a very small probability, extremely small but nonzero probability, of triggering the 'big one'" on the San Andreas fault, Emily Brodsky, a geophysicist at the University of California, Santa Barbara, told NBC News.
The papers "continue the dialogue on induced seismicity, which is great," Julia Shemeta, founder and president of MEQ Geo, a consulting firm on seismic hazards with various clients in the petroleum industry, told NBC News. But, she added, "I don't think this is a huge red light."
Shemeta was a member of a National Research Council Committee that issued as report in 2012 finding that the practice of fracking poses scant risk of triggering damaging earthquakes, but called for further research into the issue.
Scientists have known for several decades that human activity can cause the ground to shake, but the rise in earthquake frequency paralleling the rise in production of oil and gas from shale rock formations has made the issue a hot topic, Ellsworth noted.
For one, scientists don't know how big — and thus deadly — these induced earthquakes can be. "We know a lot about the process that starts an earthquake — both natural and man-made ones — but what is really difficult for us to understand at this point is how far they will run once they get started," he said.
Most induced earthquakes, like natural ones, are tiny, Ellsworth said. But a few have been large enough to feel and caused minor damage, including a magnitude 5.7 event near prague in 2011, that destroyed 14 homes and injured two people. Another study, published in Science, linked it to an injection well used to dispose wastewater from oil operations.
Fracking on the east cape of New Zealand has been prevented for now, but all this new info should add to the debate if Fracking should be allowed anywhere in NZ until further investigations have been carried out?