Quake map

This is a map of the magnitude-4.8 earthquake that struck near Wasco Feb. 23, 2016.

Scientists hired by the state to examine possible links between oil field injections and earthquakes will investigate whether such work contributed to Tuesday’s magnitude-4.8 temblor near Wasco, even as California’s top geologist ruled out any such connection Wednesday.

William Foxall, a senior scientist at Lawrence Berkeley National Laboratory, said by email the quake “will certainly be included in our state-commissioned investigation.”

Members of the research group he leads have preliminarily reviewed information the U.S. Geological Survey has provided about the quake, Foxall noted. But at this point there is not enough information “to even speculate as to the origin of the earthquake,” he wrote.

Earlier this month, a study led by a former CalTech researcher concluded oil field wastewater injections probably contributed to three Kern County earthquakes magnitude 4 and stronger on the same day in September 2005. It was among the first studies linking California earthquakes to oil field injections, though earlier research has blamed such work for seismic activity in Oklahoma.

California State Geologist John Parrish dismissed any suggestion the earthquake, centered 13.7 miles underground, could have been related to oil field activity.

“The movement on the fault was caused by tectonic stresses, not by oil field production operations. There’s no connection between this earthquake and oil field production,” Parrish said in a statement released Wednesday by the state Department of Conservation.

There are 32 injection wells within a 10 mile radius of the earthquake’s center, according to the agency. Together they pump about 3.5 million gallons of water and wastewater underground each month.

The department, whose Division of Oil, Gas and Geothermal Resources regulates petroleum production in the state, said the quake’s epicenter was more than 10 miles below any nearby injection activity.

The department recently commissioned a three-part scientific study to help guide its efforts to write new regulations for injections including those disposing of oil field “produced water,” the salty fluid that comes up from the ground along with oil. The first part of the study is expected to be released in December.

The research group, which began its work for the agency this month, includes Thomas Goebel, the lead researcher on the peer-reviewed study published Feb. 4 in the scientific journal Geophysical Research Letters. Goebel, now at the University of California, Santa Cruz, did not immediately respond to a request for comment.

California oil field injections have gained a great deal of attention in recent years, much of it negative. Regulated separately from the controversial well-completion technique known as hydraulic fracturing, or fracking, injections are generally used either to dispose of produced water and other waste or to force steam underground to promote oil production in a process called cyclic steaming.

Since July 2014, more than four dozen wastewater injection wells have been ordered closed in Kern County because of concern they were improperly exempted from federal groundwater protections. In no case was there confirmation the wells had actually contaminated sources of drinking water.

Goebel, joined by scientists at four other universities, used a hydrogeological model to analyze the three 2005 quakes along the White Wolfe fault, the formation south and east of Bakersfield that was responsible for 1952’s magnitude-7.2 Kern County Earthquake.

Their study identified what the researchers considered to be unusual seismic patterns. It concluded fluid injections by oil companies months before the quakes likely put localized pressure along the fault, and that this probably led to the earthquakes.

The U.S. Geological Survey reported Tuesday’s quake originated four miles south-southwest of Wasco and six miles west-northwest of Shafter. That puts it about 9.5 miles southwest of the Pond fault, which in that area runs northwest and southeast.

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