Swiss Earthquake Hazard
Dokuments and Maps
http://www.earthquake.ethz.ch/research/Swiss_Hazard
Swiss Hazard Map
Swiss Hazard Maps for selected return periods
For 1 Hz:
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100 years
475 years
2500 years
10000 years
For 5 Hz:
100 years
475 years
2500 years
10000 years
Other Maps and Plots
Spectral Values
Hazard Curves
De-aggregation
Ground Motion Models
The seismic hazard map of Switzerland depicts the level of horizontal ground motion (in units
of the 5% damped acceleration response spectrum at 5Hz frequency) expected to be reached
in a period of 475 years (10% exceedance chance in 50 years). The map is calibrated for rock
ground conditions, with shear wave velocities of about 1500 m/sec. The seismic hazard is
computed combining a Monte-Carlo and a logic-tree approach, which allows a full exploration
of the uncertainties. Overall, the hazard level of Switzerland ranges between 5 and 15% of
the acceleration of gravity (0.5 - 1.5 m/sec2). This level of hazard qualifies as intermediate at
a global scale.
Swiss Hazard Map
Swiss Hazard Maps for selected return periods
For 1 Hz:




100 years




100 years
475 years




Spectral Values
475 years
2500 years
10000 years
For 5 Hz:
2500 years
10000 years
Other Maps and Plots
Hazard Curves
De-aggregation
Ground Motion
Models
The seismic hazard map of Switzerland depicts the level of horizontal ground motion (in units
of the 5% damped acceleration response spectrum at 5Hz frequency) expected to be reached
in a period of 475 years (10% exceedance chance in 50 years). The map is calibrated for rock
ground conditions, with shear wave velocities of about 1500 m/sec. The seismic hazard is
computed combining a Monte-Carlo and a logic-tree approach, which allows a full exploration
of the uncertainties. Overall, the hazard level of Switzerland ranges between 5 and 15% of
the acceleration of gravity (0.5 - 1.5 m/sec2). This level of hazard qualifies as intermediate at
a global scale.
The seismic hazard map of Switzerland depicts the level of horizontal ground motion
(in units of the 5% damped acceleration response spectrum at 5Hz frequency)
expected to be reached in a period of 475 years (10% exceedance chance in 50
years). The map is calibrated for rock ground conditions, with shear wave velocities
of about 1500 m/sec. The seismic hazard is computed combining a Monte-Carlo and
a logic-tree approach, which allows a full exploration of the uncertainties. Overall,
the hazard level of Switzerland ranges between 5 and 15% of the acceleration of
gravity (0.5 - 1.5 m/sec2). This level of hazard qualifies as intermediate at a global
scale.
Swiss Hazard Map
The new Swiss Hazard Map is available as PDF document (2 MB) or as printed version in the
80x85 cm format. It can be ordered here.
Hazard Report
The new Hazard Report "Seismic Hazard Assessment of Switzerland, 2004" is available as PDF
document. A printed version can be ordered here.
Introduction
Earthquakes are a serious threat to society and human beings. In order to implement
measures to mitigate the consequences of earthquakes, the seismic hazard needs to be well
assessed and known. Seismic hazard is defined as the probable level of ground shaking
associated with the recurrence of earthquakes in a given time period. The assessment of
seismic hazard is the first step in the evaluation of seismic risk, obtained by combining the
seismic hazard with vulnerability factors (type, value and age of buildings, as well as
infrastructure, population density and land use). Seismic hazard is assessed by combining the
history of past earthquakes with the knowledge of the present seismotectonic setting and the
local properties of the waves generated by earthquakes.
We present the results of a new generation of probabilistic seismic hazard assessment for
Switzerland. This study replaces the previous intensity based generation of hazard maps from
1976. It is the first to systematically consider alleatory and epistic uncertainties and compute
spectral hazard.
Based on a revised moment magnitude earthquake catalog for the period 1300 - 2002, sets of
recurrence parameters (a, b-value and Mmax) are estimated for two models of seismotectonic
sources zones, using two different completeness reporting models. To estimate alternative aand b-value sets and their relative weighting, we introduce a novel approach based on the
Bayesian information Criterion.
Epicenter map of earthquakes in Switzerland snce 1300.
From these input parameters, we simulate synthetic earthquake catalogs of 1 Million year
duration, reflecting the difference in depth distribution between the alpine Foreland and the
Alps. Using a new predictive spectral ground motion attenuation and scaling model (Bay et al.,
2004), we estimate expected ground accelerations at 0.5 - 12 Hz for all of Switzerland and
return periods of 100, 475, 1000, 2500 and 10'000 years. Hazard maps for the frequency
range and the different return periods are found under Swiss Hazard Maps.
Switzerland is characterized by moderate seismic activity. The epicenter map shows the
instrumentally recorded earthquakes of the period 1975 to 2002 with magnitudes >= 2.5, as
well as all earthquakes since the 13th century known to have caused damage (intensity >=
VI). In this period approximately 10’000 events have been felt by the population, 12 are
known to have caused severe damage. Moderate seismicity in populated areas combined with
high vulnerability entails moderate hazard but high risk.
The hazard map for 5Hz and a return period of 475 years can be obtained for free from the
Swiss Seismological Service. The frequency of 5Hz corresponds to the portion of the spectrum
where the local soil conditions are likely to enhance seismic motion. This is also the resonance
frequency of 2 to 5 story buildings representing the largest contribution to the building stock
of Switzerland. In the map, blue to green colors indicate areas of expected moderate shaking
and damage, while red to orange highlight areas expecting more severe shaking and damage
in the next 475 years. The zones of higher hazard in Switzerland are the Wallis, the Basel
region, Graubünden and the Alpine front. This hazard map is the basic input for the zonation
of the Swiss territory and the definition of the design spectra included in the new national
seismic building code SIA 261, which is valid since 2004.
More detail about the data, methodology and results is found in the report ‘Seismic Hazard
Assessment in Switzerland 2004’ (see link at the right).
Hazard maps for the frequency range and the different return periods are found under Swiss
Hazard Maps. We also show the hazard at various sites in Switzerland as hazard curves and
uniform hazard spectra.
http://www.seismo.ethz.ch/staff/martin/BlindTest.html