The US state of Oklahoma is investigating whether a more than 20-fold jump in the number of earthquakes in the past two years is connected to a surge in fracking, the controversial drilling method used to extract shale gas, The Independent has learnt.
The number of earthquakes recorded in the
state soared from its historical average of about 50 a year to 1,047 last year and is likely to match or break that this year, said Austin Holland, a seismologist at the Oklahoma Geological Survey.
Mr Holland made his prediction in the aftermath of some of the strongest earthquakes the state has seen over the weekend, continuing a spate of seismic activity which scientists are struggling to understand.
Until last year, the highest number of earthquakes Oklahoma state had recorded was 150, in the mid-1990s.
The practice of fracking, or hydraulic fracturing, involves pumping water, sand and chemicals at high pressure into shale rock, to release the gas it holds.
