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Introduction

In the recent years, the Swiss Seismological Service (SED) has updated the Earthquake Catalog of Switzerland and prepared an electronic version for publication. The version presented here (ECOS-09) is an excerpt of the SED-database and includes all earthquakes for which macroseismic or instrumental data exists. The catalog is the result of the revision of recent earthquake catalogs for Switzerland. It encompasses – in differing degrees of completeness – the period between AD 250 and the end of 2008. The final report is available for download here.

Depending on size and location of the events, the study of earthquakes before 1975 was undertaken in three steps: historical, macro-seismic and seismological.

Firstly, historical records were used to analyze known earthquakes. All available studies, catalogs of earthquakes and macroseismic databases from Switzerland and neighbouring countries were evaluated, matched, and stored in a database. Secondly, all earthquakes where significant effects were observed in Switzerland and its surroundings were re-evaluated and the associated intensity fields were determined. Intensity points for foreign locations were imported from available compilations. Earthquakes without significant damage (if known) were systematically reviewed for the years following 1878, while those from the period preceding 1878 were processed according to the availability of historical documents. Thirdly, all earthquakes with sufficient seismologically determined intensity observations were evaluated: their strength was determined using a regression procedure to derive source parameters (epicenter, depth, epicentral intensity, maximum intensity and magnitude). At the same time Swiss earthquake seismograms from the main European earthquake observatories since the beginning of the 20th Century were analyzed to derive a relationship between magnitude and intensity.

For the earthquakes after 1975, earthquake locations from the instrumental network of SED were reviewed. Due to the continual upgrade of the instrumental network over the years, the accuracy of locations has also become more reliable. In order to complete the catalog, particularly in the border regions of Switzerland, it was supplemented with the available earthquake catalogs from neighboring countries and international agencies. Existing since the mid-1980s, digital waveforms were used to calibrate different magnitude scales of other seismological observatories with the Richter magnitude (ML scale) of the SED. In addition, for all earthquakes a homogeneous magnitude estimate, based on the moment magnitude (Mw), was derived.

The earthquake catalog ECOS-09 and the associated macroseismic database is available online through the website of the Swiss Seismological Service. The data covers a region that includes the area of the Swiss national map at a scale of 1:500 000 plus a buffer zone of 30 kilometers (Swiss coordinates (km): 460-882 / 20-350; Geographical coordinates approx.: 5.6-11.1E / 45.4 -48.3N). The expected completeness of ECOS is regional and temporal and varies for different earthquake intensities.

The ECOS-09 catalog corresponds to the level of knowledge about earthquakes in Switzerland in 2009. Information about recent earthquakes is also available on the website of the SED. This information represents the current state of knowledge and is not explicitly part of the ECOS-09 catalog.

Older versions of Swiss earthquake catalogs:

May 20, 2011 SED (df).