Earthquakes in Switzerland and surrounding regions during 2011

This report of the Swiss Seismological Service summarizes the seismic activity in Switzerland and surrounding regions during 2011. During this period, 522 earthquakes and 92 quarry blasts were detected and located in the region under consideration. With a total of only 10 events with M L ≥ 2.5, the seismic activity in the year 2011 was far below the average over the previous 36 years. Most noteworthy were the earthquake sequence of Sierre (VS) in January, with two events of M L 3.3 and 3.2, the M L 3.3 earthquake at a depth of 31 km below Bregenz, and the M L 3.1 event near Delémont. The two strongest events near Sierre produced shaking of intensity IV.