GUTHRIE, Okla. (AP) — The U.S. Geological Survey has recorded seven small earthquakes shaking central Oklahoma in a span of about 14 hours.
The temblors are part of an increase in earthquakes across Oklahoma, Texas and Kansas that some scientists say could be connected to the oil and gas drilling method known as hydraulic fracturing, and especially the wells in which the industry disposes of its wastewater.
Sunday's quakes ranged from magnitude 2.6 to 2.9 and were centered in the Guthrie, Jones and Langston areas, 15 miles to 30 miles northeast of Oklahoma City. The USGS said the quakes were recorded between 7:57 p.m. Saturday and 9:51 a.m. Sunday. No injuries or damage were reported.
Those follow four other quakes, including a 4.3-magnitude temblor near Langston recorded shortly after noon Saturday. The other Saturday morning quakes ranged in magnitude from 2.9 to 3.2.
Seismologists know that hydraulic fracturing, or fracking — which involves blasting water, sand and chemicals deep into underground rock formations to free oil and gas — can cause microquakes that are rarely strong enough to register on monitoring equipment.
However, fracking also generates vast amounts of wastewater, which is pumped into injection wells thousands of feet underground. Scientists wonder whether they could trigger quakes by increasing underground pressures and lubricating faults. Another concern is whether injection well operators could be pumping either too much water into the ground or pumping it at exceedingly high pressures.