HuffingtonPost.com reports the USGS has termed the swell an "earthquake swarm," and on Tuesday, it ruled out the possibility this sharp increase is a naturally occurring phenomenon.
"We've statistically analyzed the recent earthquake rate changes and found that they do not seem to be due to typical, random fluctuations in natural seismicity rates," USGS seismologist Bill Leith said in a statement. "This is in contrast to what is typically observed when modeling natural earthquake swarms." Instead, the USGS suggests "injection-induced seismicity" may be playing a role. The term refers to pumping wastewater produced by fracking and other oil and gas projects into storage deep in the ground, HuffingtonPost.com reports.
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