Mrdalsjkull glacier, South Iceland, where Katla volcano is located. Several smaller tremors have followed. Yesterday, October 5, at 8:22 am, an earthquake of magnitude 3.8 hit the northern part of the Brarbunga caldera in Vatnajkull glacier. It was followed by several tremors, the largest of which measured 3.0.
http://icelandreview.com/news/2016/10/06/katla-quivers-0