Historical seismology
Overview
Where small earthquakes occur, larger events can happen sooner or later. Since precaution against future catastrophes is based on insights about past disasters, the study of historical earthquakes is not only of a purely historical interest. The exact knowledge of the location of earthquakes, their effects and the damage they caused, allows conclusions about their strength. These parameters can be used as a basis for the estimation of a region’s seismic hazard and can give indications about local effects of subsoil-related ground motion amplification, etc.
In the Swiss area the frequency of occurrence of damaging earthquakes is relatively low. Therefore long periods of time have to be studied in order to gain the amount of data necessary for hazard and risk calculations.
Instrumental measurement only provides reliable data on seismic activity in Switzerland since 1975, thus the assessment of seismic hazard for Switzerland relies chiefly on the record of past earthquakes handed town to us by a variety of historical sources.
Historical Seismology at the SED
ECOS-09
Earthquake Catalogue of Switzerland (ECOS-09)In order to assure the dependability of this historical information the SED established the research field of historical seismology in 1999 as a sub-discipline. From that time on an interdisciplinary team of historians, seismologists, and database-experts was compiling a first historically qualified catalogue of Switzerland’s earthquakes from ancient times to the instrumental period (ECOS-02) with an update made public in 2011 (ECOS-09).
The main focus of the historical studies carried out for the compilation of the earthquake catalogues ECOS-02 and ECOS-09 was put on the earthquakes occuring in the time period from the first millennium to the 1870s. Furthermore the events of the 20th Century with the largest extent of damage have been addressed (Sierre 1946, Sarnen 1964).
Present research topics
Revision of the Swiss Earthquake Catalogue 1878–1960
A major research subject of the next years is the reexamination of the slightly damaging earthquakes of the pre-instrumental respectively the early-instrumental era of scientific earthquake research (1870s to 1970s). With regard to their higher frequency of occurrence and an increasing documentary activity (in 1878 the Swiss Earthquake Commission – the precursor organization of the SED – was established) an examination of this class of events is promising a broad dataset yet to be assessed in-depth.
Historical context of earthquake data collection
To ensure a correct interpretation of scientific and non-scientific earthquake records of this time period it is of great importance to know the historical context of their production. Special attention is therefore put on different aspects of the history of science, scientific networks and the development of earthquake observation at the SED. The relationship between earthquake observation by macroseismic surveys relying on the population’s reports and the development of a network for instrumental earthquake monitoring in the 20th century is of special interest in that respect.
Interdisciplinary research
Furthermore, the succession of fore- and aftershocks as well as earthquake sequences are specifically targeted. Besides that, the interdisciplinary cooperation of the historical section with the neighboring disciplines, most notably engineering seismology, are enforced in practical projects e. g. by comparing parameters deduced from historical sources with physical measurements.
Contact: Remo Grolimund
