Stefan Fritsche, zusammen mit Donat Fäh und Domenico Giardini

Within this multidisciplinary project we investigate large historical earthquakes in Switzerland: Visp 1855, Siders 1946 and Sarnen 1964. All events caused moderate (1946, 1964) to heavy damage (1855). The study focuses on the distribution of damage and on the occurrence of possible site effects.

Our approach combines historical inquiries with results of geological and geophysical investigations. An extraordinary wide and complete basis of contemporary historical sources exist for two of the events (1855, 1964), while for the 1946 earthquake only few detailed descriptions are available. For the 1855 and 1964 events, several hundred affected buildings are mentioned in different sources. This allows a reconstruction of the distribution and the extent of the damages. Furthermore a large number of descriptions of effects in nature are at hand, which allow to overview the secondary effects such as rock fall and slope instabilities in the epicentral areas. The local ground conditions are evaluated by the analysis of available borehole information and measurements using ambient vibration recordings on single stations and arrays.