New Study Links Texas Quakes to Fracking Wells
Geophysicsts saw in a new study that a 2012 earthquake in East Texas was caused by wastewater injection, a waste product practice by the fracking industry.
Registering 4.8 on the Richter scale, the earthquake was the strongest in the recorded history of the region. At the time, scientists told CNN they suspected nearby injection wells were responsible. A new study in Science, "Surface uplift and time-dependent seismic hazard due to fluid injection in eastern Texas," backs up that hypothesis using Interferometric Synthetic Aperture Radar (InSAR).
InSAR is a "technique for mapping ground deformation using radar images of the Earth's surface that are collected from orbiting satellites," according to the U.S. Geological Survey. It's regularly used to monitor volcanoes. In East Texas, it could detect changes in the of Earth's surface at the scale of centimeters.
Setting InSAR's eye on four high-volume wells used for wastewater disposal, the researchers began to track the changes in the Earth. Wastewater injection wells handle a byproduct of fracking, which study co-author William Ellsworth compares to "ancient ocean water" in that it is "too salty and too contaminated with other chemicals to treat economically, so the only viable solution at present is to put it back underground." The wells then push that wastewater thousands of feet underground, although distances vary per well.
Looking at wells close to the earthquake's epicenter determined that wastewater injection from shallow wells resulted in detectable ground uplift at distances up to 5 miles. The deeper wells affected pore pressure, which refers to "the pressure exerted by a column of water from the formation's depth to sea level." By creating an impasse in the rock, the injection well forced the pore pressure downwards until it hit an ancient fault line.
There was only one injury in the 2012 quake, which destroyed a few TVs and chimneys. But, Ellison notes, the "recent upturn in seismicity in Oklahoma and Kansas commonly happens where injection occurs close to the crystalline basement, so we're getting lots of earthquakes in those places." Where there are injection wells, it seems, earthquakes have the potential to follow.
Source: Stanford
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