Responding to a rising number of earthquakes, the U.S. Geologic Survey is updating its maps to distinguish between naturally occurring earthquakes as well as those induced by humans.
It’s the first time the USGS has taken such measures to make the distinction, recognizing the difference between the ground-shaking hazards. In the past, USGS maps only identified natural earthquake hazards.
It’s also the first one-year outlook for the nation’s earthquakes, supplementing existing USGS assessments that have historically provided a 50-year forecast, USGS officials report.
The report shows that approximately 7 million people live and work in areas of the central and eastern U.S. (CEUS) with potential for damaging shaking from induced seismicity, according to the USGS. That is mostly concentrated in Oklahoma, Texas, New Mexico, Kansas, Colorado and Arkansas.
Within a few portions of the CEUS, the chance of damage from all types of earthquakes is similar to that of natural earthquakes in high-hazard areas of California.
Future research could take a more detailed look at induced seismicity in the west, including in California at The Geysers, Brawley or the Los Angeles Basin, officials report.
The CEUS has experienced the most significant U.S. increase in seismic activity due to induced earthquakes in recent years, according to the USGS.
Induced earthquakes are triggered by human activities, with wastewater disposal being the primary cause for recent events in many areas of the CEUS. Wastewater from oil and gas production operations can be disposed of by injecting it into deep underground wells, below aquifers that provide drinking water.
USGS scientists only distinguished between human-induced and natural seismicity in the CEUS. In the west, scientists categorized all earthquakes as natural. Scientists also used a different methodology in looking at the CEUS compared to the west.