The Sierre earthquake series

The Sierre earthquake series

A swarm of 31 earthquakes began near Sierre on 8 January 2011. Sixteen of these earthquakes occurred in the first five hours, including two with magnitudes of 3.3 and 3.2. A further nine events followed in the next two weeks and the remaining six over the rest of the year. The individual seismic foci were located at depths of 6 to 7 km on two vertical, slightly staggered fracture segments running west to east (W-E), with a total surface area of approximately 800 x 400 m.