Tuesday, November 8, 2011
Oklahoma has recently experienced a spate of earthquakes. (Those outside of the state may even have felt some of these rumblings; apparently they extended as far as Wisconsin.) People tend to expect tornadoes in Oklahoma, but not earthquakes. (On Monday the state experienced another earthquake and some tornadoes, too, just to add some excitement to the mix.) The earthquake activity has led some people to ponder the causes of this uptick in odd rumblings of the earth. One Associated Press article notes some speculation of a connection between oil and gas development and earthquakes. From my extremely limited perusings and past discussions with a geologist, and with the added reminder that I have no knowledge of geology, there seems to be a consensus that underground injection control wells for the disposal of oil and gas--those that contain salty brine from wells, for example--can cause very small, localized earthquakes if the wells are drilled in certain areas (fault zones, for example). The Oklahoma Geological Survey states: "Cases of clear anthropogenically-triggered seismicity from fluid injection are well documented with correlations between the number of earthquakes in an area and injection, specifically injection pressures, with earthquakes occurring very close to the well." This doesn't tell us, of course, whether UIC wells ever could lead to quakes of a higher magnitude felt across larger areas, such as those that we've recently experienced in Oklahoma. As with many questions, more research is needed, it appears. It seems unlikely that we'll ever really figure out earthquakes: It was interesting to learn, for example, that scientists have trouble predicting when earthquakes will occur--let alone fully understanding their causes.