This is a short note on the Hengill volcano man-made earthquake swarm.
The earthquake swarms that have been taking place in Hengill volcano are man made due to Orkuveita Reykjavíkur pumping down water at the depth of 2500 meters or more (down to 4000 meters from what I have read). It is clear that Orkuveita Reykjavíkur (short name OR) does not have any option but to continue this water pumping, as it is mandated that they do so in there operation permit. They have been doing this for some time now. But when they started using new drilling holes to pump down water the earthquake swarms started to happen. The people at OR claim that it is unlike that this earthquake swarms are going to grow in size and magnitude. I do not agree with that assessment.
It is my view that increased water pumping into the bedrock is going to increase earthquake activity. This has been agreed on by geologist that are not connected to OR or the government. But the largest earthquake that this area can make is Mw 6.0 in size according to a estimate on this area. So far, the largest earthquakes have been up to ML 4.0 in size so far. A jump in magnitude from ML3.5 size that was in earlier pumping was done.
There is also risk of pollution of the groundwater from heavy metals in the hot water (lead, zinc, copper and others). But this risk also seems to have been underestimated. As they claim that pumping down the water below the 800 meters groundwater line does not affect the groundwater. But it seems that no studies (that I know) have been done to confirm this.
News on Rúv about this.
Aukin dæling mun auka skjálftavirkni (Rúv.is, Icelandic)