A new report by the United States Geological Survey (USGS) shows that approximately 7 million people live and work in areas of the central and eastern United States vulnerable to man-made earthquakes. The six states that face the highest risk include Oklahoma, Kansas, Texas, Colorado, New Mexico, and Arkansas. This is the first time the USGS has released maps identifying both natural and human-induced earthquakes.
Induced earthquakes are triggered by human activities and wastewater disposal from hydraulic fracturing, colloquially know as fracking, is the primary cause. In fracking operations, wastewater is injected at high speeds into deep, underground wells. This can put increased pressure on nearby fault lines.
The central United States has undergone the most dramatic increase in seismicity over the past six years. From 1974 to 2008 there were an average of 24 earthquakes of 3.0 magnitude and larger per year. From 2009 to 2015 the rate steadily increased, averaging 318 per year and peaking in 2015 with 1,010 earthquakes. Just through March 2016, there have been 226 earthquakes of magnitude 3.0 and larger in the central United States. The largest earthquake to date is a 5.6 magnitude in 2011 in Oklahoma, near several active injection wells.
Local health departments and emergency response personnel can use this report to make more informed decisions, to assess vulnerability, to and provide safety information to those in potential danger. People living in higher hazard areas, particularly those areas not susceptible to natural earthquakes, should learn how to be prepared in case of an earthquake.
