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The First National Earthquake Risk Model for Switzerland

Description: 

The first open-access seismic risk model for Switzerland at a national scale was released in March 2023 and this contribution summarizes the process of model building, key results, model sensitivities, communication aspects and impact. Switzerland is a country with moderate earthquake hazard but a high earthquake risk, because of the high population density, high building costs, vulnerable historical building stock and numerous areas of high site amplification. The 2020 Risk Report published by the Swiss Federal Office for Civil Protection ranked earthquakes as the third most significant risk faced by Switzerland, after electricity shortages and pandemics.

The federal council commissioned the Earthquake Risk Model Switzerland (ERM-CH) in 2017 and the Swiss Seismological Service (SED) was designated as the lead agency to build and operate the model. A total budget of about 5 Mio CHF was invested to enhance all relevant components of the risk modelling chain, with a special focus on enhancing the resolution and accuracy of the local site amplification model. The model uses an extensive logic tree to capture uncertainty in a consisted and harmonized way across all model components. We also payed close attention to ensure consistency with other products of the SED, such as rapid ShakeMaps. Using the new model, the SED will now distribute within one hour of a significant earthquake a rapid impact assessment. The model will serve a wide range of potential stakeholders, including civil protection at national and cantonal levels, the insurance industry, engineering companies as well as the public. The main products such as a risk index map were tested through focus groups and systematic surveys for understandability and clarity. The model results show,as expected, that seismic risk is substantial and focused on areas of high population density and poor soil condition. This key message has a substantial impact on earthquake awareness in Switzerland.

Session: Advances in Probabilistic Seismic Hazard Analysis and Applications

Type: Oral

Date: 4/19/2023

Presentation Time: 02:15 PM (local time)

Presenting Author: Stefan Wiemer

Student Presenter: No

Invited Presentation: Yes

Authors