Man-made earthquakes

Many places in the world get earthquakes. The very low magnitude ones are surprisingly common. But the high magnitude ones are uncommon. But when the number of earthquakes increases dramatically, it’s time to get worried about what’s going on.

The New Yorker has an article on the number of earthquakes increasing in Oklahoma. In 2008 there were one or two magnitude 3.0+ earthquakes each year. Now, it’s one or two magnitude 3.0+ earthquakes each day. What’s changed? What could be causing this? The answer is fracking. Pumping a slurry of water, sand, and chemicals into the earth at high pressure helps release natural gas.

William Ellsworth, a research geologist at the United States Geological Survey, told me, “We can say with virtual certainty that the increased seismicity in Oklahoma has to do with recent changes in the way that oil and gas are being produced.” Many of the larger earthquakes are caused by disposal wells, where the billions of barrels of brackish water brought up by drilling for oil and gas are pumped back into the ground. (Hydraulic fracturing, or fracking—in which chemically treated water is injected into the earth to fracture rocks in order to access oil and gas reserves—causes smaller earthquakes, almost always less than 3.0.) Disposal wells trigger earthquakes when they are dug too deep, near or into basement rock, or when the wells impinge on a fault line. Ellsworth said, “Scientifically, it’s really quite clear.”

Humanity is causing more and stronger earthquakes. What are we going to do about it?