Nachbeben in der Umgebung des Epizentrums sind in den nächsten Tagen und Wochen mit Sicherheit zu erwarten, einige dieser Nachbeben werden deutlich spürbar sein oder  gar weitere Schäden anrichten. Im direkten Schadengebiet ist mit Beeinträchtigungen der Infrastruktur zu rechnen. Für offizielle Reisewarnungen ist das EDA zuständig. Personen, die planen in nächster Zeit in die betroffenen Gebiete zu reisen,  sollten sich bei konkreten Fragen an ihren Reiseveranstalter wenden.

Die Wahrscheinlichkeit, dass es in den nächsten Tagen oder Wochen zu einem weiteren, ähnlich starken oder gar noch grösseren Beben in der Region Kos/Bodrum kommt, ist sehr gering. Allerdings ist sie erfahrungsgemäss deutlich erhöht verglichen mit dem langjährigen Mittel.

Erdbeben der Stärke 6 und mehr sind in der gesamten Ägäis und den angrenzenden Gebieten im Prinzip überall und jederzeit möglich, die Region hat generell eine der höchsten seismischen Gefährdungen in Europa und im Mittelmeerraum.

Seit 1900 haben sich im Umkreis von ca. 150 km um das Epizentrum des aktuellen Bebens sieben Erdbeben mit Magnituden von grösser als 6.5 ereignet (Quelle: International Seismological Center). Das stärkste wies eine Magnitude von 7.5 auf und ereignete sich 1956 südlich der Insel Amargos (ca. 130 km westlich des aktuellen Bebens). 1926 ereignete sich ein Beben der Stärke 6.9 ca. 15 km westlich von Kos.

The seismicity in this zone has been elevated since 2016 and several events up to magnitude 2.7 were felt in 2016 and 2017, the last one on 13th May. Saturday’s earthquake was clearly stronger. The M4.3 is part of a sequence that we expect will continue with lower magnitude events that will last for weeks, or even months. Some of them, like that at 11:29 (magnitude 2.6) will be felt in the epicentral region, and the population should expect additional quakes in the coming days. An event as strong as that of Saturday or even stronger cannot be ruled out but has a relatively low probability.

The earthquake is related to the rupture of a normal fault (extension) oriented E-W, as the previous events recorded since 2016. A broadband moment tensor inversion also suggests a shallow event with moment magnitude Mw4.0 and a normal focal mechanism. The station SCOD in the town of Château d'Oex recorded a strong motion acceleration of 1.5m/s² – this is the second largest instrumental recording in Switzerland.

Historically, this region has been hit by an earthquake in 1770 also close to Château d’Oex, for which the magnitude was estimated to 5.2 and the epicentral intensity of VI (obtained from the damages). By comparison, Saturday’s earthquake has an epicentral intensity of V.

In Switzerland, an earthquake of magnitude greater than 4 occurs on average every year. Another earthquake of magnitude 4.6 occurred in March this year in canton Glarus with relatively similar consequences across a larger area.

The colored squares on the map show where the earthquake was felt and reported to us. In the background, the instrumentally recorded intensity is shown.

Seismic data have provided important early constraints on the slide event. A key station is NUUG, in the village of Nuugaatsiaq, one of the three stations in northwestern Greenland built and operated by the Swiss Seismological Service with the support of SNSF. These stations not only recorded the landslide signal but also the sea waves inundating the village as a result of the fjord seiche. Additional information about the landslide signals can be found here.

Further information about the seismic monitoring of glaciers, the primary purpose of this seismic network in Greenland, can be accessed here.

Based on the seismic hazard, the risk model takes account of the influence of the local subsurface and of the vulnerability and value of buildings and infrastructure. In future it will enable cantonal and national authorities to draw up improved risk overviews and use them to optimise their planning. Besides prevention, the model will serve to quickly assess where damage can be expected in the occurrence of an event. The development of the model is being financed by contributions from the FOEN, FOCP and ETH.

In addition, the earthquake risk management programme for the years 2017 to 2020 also provides for the following seismic measures, which are described in detail in the federal government press release and will aim to:

• ensure institutionalised cooperation at the federal level;
• complete the renewal of national earthquake measuring systems;
• improve the bases for hazard assessment and seismic safety requirements;
• to inventorise the earthquake-resistance of important federal buildings in Switzerland and abroad;
• to safeguard the quality of earthquake protection measures in construction projects involving Switzerland's Federal Building and Property Services;
• to draft principles and criteria for the assessment and treatment of cantonal applications for special federal financial aid in the event of an earthquake;
• to draw up a concept for the establishment and operation of a claims organisation in conjunction with insurance companies and the cantons.

In addition to devising the seismic risk model, the SED is responsible for renewing Switzerland's national seismic network.