There was seismic activity by Bárðarbunga last night, RÚV reports. At about a quarter to nine, an earthquake of magnitude 3.8 shook the area. Then, shortly after 10 pm, another followed which measured 3.7.
The earth shook on Hellisheiði mountain as well, where the Hellisheiði Geothermal Plant is located. At about 10:30 pm, an earthquake of magnitude 3.6 hit the area. It was felt in Hveragerði, Mosfellsbær and Kópavogur. Twenty minutes later, a tremor of magnitude 3 followed. The area has been affected by a series of tremors in recent days, the largest of which hit yesterday. The seismic activity may be caused by hydro-fracking, which is practiced at Húsmúli lava dome, where the largest quake occurred.
The practice involves pumping water into a borehole, which fractures the hot rock close to the magma. That increases permeability, allowing for a greater circulation of water. There are concerns that such methods increase seismic activity.
According to E&T, research at the University of Iceland has shown that “ever since operations at the Hellisheidi Geothermal Plant began in 2006, the reinjections of geothermal fluid, hot water and steam back into the geothermal reservoir have been accompanied by increased microseismicity.”