2012-01-05
Small earthquake sequence close to Filisur GR
The Swiss Seismological Service registered since New Year's Day a series of small earthquakes northeast of Filisur, GR. The strongest earthquakes so far had a magnitude of 3.2 (1th January, 16:33 Swiss time) and 3.5 (2th January, 02:42). Both earthquakes were clearly felt by some people. Until the evening of 3th January the SED recorded 7 earthquakes in close proximity. The depth of the sources is not well constrained. The similarity of the recorded signals suggests, however, that all sources are located at approximately the same depth between 5 and 10 km below sea level, similar to previous earthquakes in this region.
For this region such earthquake sequences are not unusual. At this moment it can not be determined whether this sequence will continue for months as the ones in Sertig (2003) or Paspels (2007 - 2009) or if it will stop in the next few days.
The probability that a larger earthquake may occur in the near future is not significantly enhanced by this sequence.
The last stronger earthquake (magnitude 5) occurred in November 1991 in Vaz and caused slight damage to some buildings.
Even if stronger earthquakes (magnitude 5 to 6) happen only very rarely in Switzerland they may in principle occur anywhere anytime.
