ZURICH. Central Switzerland was woken before dawn on Sunday by one of the strongest earthquakes of the year. The Swiss Seismological Service at ETH Zurich measured a magnitude of 4.0, with the epicentre around five kilometres northeast of the Klausenpass, near Linthal in canton Glarus, at a shallow depth of about two kilometres. The quake struck at 4.37am local time.
The tremor was clearly felt across central Switzerland, and reports reached the seismological service from the cantons of Bern, Aargau, Ticino, Zurich and Graubünden. A first automated assessment suggested it may have been felt across much of the country. Barely ten minutes later a second tremor of magnitude just over 1.0 followed at the same spot, too weak for the population to notice.
By mid-morning, the Glarus cantonal police had received no reports of damage. Minor damage near the epicentre is possible in isolated cases after a quake of this magnitude, typically cracked plaster or fallen objects, but none had been confirmed.
Aftershocks expected
The seismological service expects further aftershocks in the coming hours and days, some of which may be felt. A quake of similar or even greater magnitude is considered unlikely, though not impossible, and residents of the region are advised to secure loose objects as a precaution.
A valley with form
Sunday’s earthquake struck at nearly the same place and depth as the Linthal quake of March 2017, which reached magnitude 4.6 and was felt across large parts of Switzerland without causing significant damage. The Glarus Alps sit in one of the country’s more active seismic zones, where the African and European plates continue their slow collision.
Switzerland records between 1,000 and 1,500 earthquakes a year, an average of three to four a day. Only ten to twenty of them, those with magnitudes of 2.5 or higher, are strong enough to be felt. Sunday’s quake belongs to the small annual group that reminds the lowlands that the Alps are still under construction.