DENVER (CBS4) – A new USGS map identifies potential ground-shaking hazards from both human-induced and natural earthquakes for the first time. In the past, these maps only identified natural earthquake hazards.
Induced earthquakes refer to those caused by human activities, with wastewater disposal the primary cause of recent events in many areas of the central and eastern U.S. They are triggered when oil and gas operations dispose of the wastewater by injecting it into deep underground wells, below the aquifers that provide drinking water.
“By including human-induced events, our assessment of earthquake hazards has significantly increased in parts of the U.S.,” said Mark Petersen, Chief of the USGS National Seismic Hazard Mapping Project, in a statement.
The report shows that 7 million people live and work in areas of the central and eastern U.S. that are at risk of damaging shaking from induced seismicity.
Of the six states facing the highest hazards, Colorado is listed fourth. From highest to lowest: Oklahoma, Kansas, Texas, Colorado, New Mexico, and Arkansas.
“In the past five years, the USGS has documented high shaking and damage in areas of these six states, mostly from induced earthquakes,” said Petersen.
The report also shows a one-year outlook for the country’s earthquake hazards, a supplement to the existing 50-year forecast. The model estimates where, how often, and how strongly earthquake ground shaking could occur in the U.S., and the shorter time frame is more suited to induced earthquake activity which is subject to commercial and policy decision.
According to the USGS, the central U.S. has undergone the most dramatic increase in seismicity over the past six years. From 1973 – 2008, the number of earthquakes with a magnitude 3.0 and larger averaged 24. In 2015, there were 1,010.
This increase is due to induced earthquakes, which prompted scientists to include the distinction in this 2016 forecast for the central and eastern U.S.