For a long time science has claimed that the disposal of gas and oil wastewater plays a significant role in the alarming number of earthquakes recorded in the last years. Finally Oklahoma’s state government has acknowledged that this is true.
Quakes triggered by man have recently shaken regions which were once stable such as Oklahoma, Texas, Ohio, New Mexico, Colorado, Kansas, Alabama and Arkansas. Experts say that the enhanced seismic activity is in most of the cases caused by the oil and gas industry which injects wastewater deep underground. This can activate formant faults. A few incidents are generated by hydraulic fracturing. This involves pumping huge quantities of chemicals, water and sand into rock formations in order to free gas and oil.
Kishor Jaiswal from the U.S. Geological Survey (USGS) together with colleagues from the California Geological Survey, FEMA (the Federal Emergency Management Agency) and USGS he examined the nation’s earthquake risk. In order to do so the researchers combined the 2014 National Seismic Hazard Maps with a global population database known as LandScan. Using data from the 2010 Census and the replacement-cost values for buildings recorded in 2012 the investigators estimated the possible financial losses which come from earthquakes. It seems that in the 48 contiguous states the economic hit caused by building damage amounts to $4.5 billion and 80% of the losses were reported in Washington, California and Oregon.
The study did not focus on man-made quakes. However Jaiswal said:
“There are 140 million people exposed to earth-shaking hazards, but that number could be even higher if you include induced seismicity.”
The report made by the Geological Survey is the first one to look at where the man-made quakes take place. It seems that Oklahoma is the most seismically active region of the 48 states. In the mid 2000s before Oklahoma’s oil and gas boom only one and a half of the earthquakes in the state exceeded magnitude 3.0. Last year Oklahoma experienced 585 quakes of 3.0 or higher. This is 600 times the seismic rate of the past.
The president of Oklahoma Oil and Gas Association, Chad Warmington, declared that there may be a link between disposal wells and earthquakes, but he confessed that industry regulators, state residents, lawmakers and researchers are still not sure to what extent water injections affects Oklahoma’s underground faults.
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