Historical Earthquake Catalogue of Switzerland

The following is taken from the MECOS website,
"http://hitseddb.ethz.ch:8080/ecos09/index.html".

The Swiss Seismological Service (SED) has prepared the earthquake
catalogue of Switzerland for publication on the Internet. It is an
extract of the computerised data bank of the SED and contains all
events with intensity V and higher, for which macroseismic
observations or other relevant historical documents are available.

The catalogue is based on the data collection prepared in 1977 for the
first probabilistic seismic hazard map of Switzerland. Since 1977 the
catalogue was used for scientific purposes, modified with respect
to errors and updated for the period after 1977. The epicentral
intensities and the associated uncertainties have been re-assessed for
major events with intensity VII or larger. In this new form it was
used for a second hazard assessment study (Ruettener, 1995), for the
uniform seismic hazard map of Germany, Austria and Switzerland (DACH -
Gruenthal, Mayer-Rosa & Lenhardt, 1998) and within the framework of
the Global Seismic Hazard Assessment Project (GSHAP).

The completeness of the MECOS varies through time for different levels
of intensity. The catalogue is estimated to be complete for the
following time periods and intensities:

Intensity V: 1875 - today

Intensity VI: 1650 - today

Intensity VII: 1575 - today

Intensity VIII and IX: 1300 - today

The period 1021 - 1300 is incomplete for all intensity levels and
uncertain with respect to the given parameters.

For the period after 1975 also events without macroseismic
observations but with instrumentally determined magnitudes of 3.0 and
larger have to be taken into account. These earthquakes are contained
in the second part of the ECOS, the Instrumental Earthquake Catalogue
of Switzerland (IECOS). This catalogue is published in the same web page.

The root classification system developed for the European BEECD
catalogue is used in the MECOS to qualify the supporting data that are
used for the determination of earthquake parameters.

As a general principle of the MECOS only macroseismic
determinations of earthquake parameters are used. No attempt was made
to convert epicentral intensities into magnitudes. Whenever magnitudes
are preferred, a simplified conversion formula M = 0.5 * Io + 1.5 is
recommended, assuming a typical focal depth between 5 and 15 km. This
assumption is supported by the fact that the majority of all
instrumentally recorded earthquakes in Switzerland between 1975 and
1999 is located within this depth range.

In the catalogue a two-digit format is used for the intensity
information. The second digit reflects merely the uncertainty in the
determination of the intensity. A value of 65 e.g. indicates that the
epicentral intensity could only be determined between the values 6 and
7, with no preference for one of the values.

This catalogue represents the knowledge on earthquakes in Switzerland
and surrounding areas by 1999. It is intended to upgrade this
catalogue whenever a significant amount of new or improved
information becomes available.