Move over California, there’s a new US earthquake capital.
According to the Center for Investigative Reporting, Oklahoma had three times as many earthquakes as California and remains well ahead in 2015.
In California, earthquakes always have been relatively common, but in Oklahoma, they were much more rare – at least until 2009.
Hydraulic facturing, or fracking, the process of drilling and injecting fluid into the ground at a high pressure to fracture shale rocks to release natural gas inside, is believed to be the major factor in increasing seismic activity in the Midwest.
Though earthquakes have proven more deadly on the West Coast, none in the Midwest have resulted in deaths, the report notes.
The largest Midwest quake in recent years – a magnitude 5.7 – was centered near Prague, Oklahoma, on Nov. 5, 2011, according to the U.S. Geological Survey.
Scientists have long assumed that the rate of earthquakes in a given location was constant, but the rapid increase in seismic activity in places like Oklahoma is fundamentally altering how experts plan for seismic risk. The U.S. Geological Survey’s current models of seismic hazards intentionally ignore quakes attributed to “induced seismicity.”