Earthquakes in Switzerland and surrounding regions during 2003

Abstract

This report of the Swiss Seismological Service summarizes the seismic activity in Switzerland and surrounding regions during 2003. During this period, 532 earthquakes and 118 quarry blasts were detected and located in the region under consideration. With 30 events with ML ≥ 2.5, the seismic activity in the year 2003 was slightly above the average over the last 29 years. As in previous years, most of the seismic activity was concentrated in the Valais and in Graubünden. In addition, several earthquakes occurred along the northern front of the Alps. The strongest event, with ML 4.0 and epicentral intensity V, occurred in the area of Urnerboden, on the border between the cantons Uri and Glarus. Two earthquakes with ML 3.9 occurred in the Valais near the town of Salgesch and south of the Sanetsch Pass. In Graubünden, the Sertig valley south of Davos was the site of a sequence of 51 earthquakes that included three events with magnitudes between ML 3.6 and 3.9.