Scientists and the oil and gas industry have known about induced seismicity, or induced earthquakes, since the 1960s. One early and telling example was the disposal of warfare chemical waste in a deep well at the Rocky Mountain Arsenal near Denver in the US. Earthquakes followed, with the largest pegging 4.8 on the Richter scale about a year after the well was shut down in 1966.

Four decades on, as shale gas exploration took off in the US, geoscientists noted an uptick in US seismic events.

Robert Williams, US Geological Survey geophysicist Photo: USGS
“There was an increase in the rates of earthquakes in the central US starting in about 2008, and scientists started looking into it,” says Robert Williams, US Geological Survey (USGS) geophysicist and co-ordinator for the USGS’s Earthquake Hazards Program for the Eastern US.