Photos are everywhere today of wine bottles, and in some cases wine barrels, broken on the floors of Napa Valley, the famous wine region in California--dashed to the ground by a magnitude 6.0 earthquake that struck there early Sunday.
News outlets are also filing regular reports from Iceland, where thousands of small earthquakes have occurred in the past week in the region around the Bardarbunga volcano. Geologists say the tremors are being caused by magma that is moving below ground there, and they are using the locations of the quakes to track the magma’s movement.
Of course central California is close to major geological faults we’ve known about, and it makes sense that massive volumes of moving magma would shimmy the surface above. But increasingly, human activity is causing earthquakes as well. A magnitude 5.1 quake in Spain in 2011 that leveled a town and killed nine people has been tied to farming. For decades many farmers pumped so much water up from below ground for irrigation that the water table dropped by as much as 250 meters, and scientists maintain that the change in water pressure caused faults to shift, triggering an earthquake.
Pumping volumes of wastewater from fracking operations back underground has been blamed for an earthquake in Ohio. Oil drilling has been implicated in quakes in California, Oklahoma and Illinois. And water piling up behind new dams in China has been sited as the cause of temblors there.
More on how humans are shaking the earth is in the Scientific America Instant Egghead video below.