Wednesday, March 30, 2016

Fracking: Human-caused earthquakes pose threat to 7m Americans

Around 7 million people in the US live in areas at risk of damaging, human-induced earthquakes that are often linked to fracking, a report said Monday.

Because the US Geological Survey (USGS) is including human-triggered earthquakes on its forecast maps for the first time, the odds of damaging shaking in certain parts of the country are much increased for 2016, it said.

The 7 million people who are at elevated risk live in central and eastern US, which has seen the most significant increase in human-triggered seismic activity, according to the USGS.

While some western regions are also experiencing induced earthquakes, these do not  significantly change the hazard level there because natural earthquakes are prevalent.

The primary cause for human-induced earthquakes in many parts of the central and eastern US is wastewater disposal. Such wastewater is linked to hydraulic fracturing, or fracking, the process of shooting water mixed with sand and chemicals into the earth to crack rock formations to bring up oil and natural gas.

But along with the oil and gas comes plenty of brackish water, which is disposed of by injecting it into separate wells that are dug as deep as 1 kilometer below ground.
  • The unnatural addition of the water can change pressure along fault lines, causing slips that make the Earth shake, experts say.
The USGS said the states at highest risk of induced seismic activity are Oklahoma, Kansas, Texas, Colorado, New Mexico and Arkansas. Oklahoma and Texas are the states with the largest population exposed to the effects of human-triggered earthquakes, it said.

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