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Broadband waveform simulations of earthquake scenarios in the Swiss Molasse basin using the BBP tool from SCEC

Maria Koroni, Miroslav Hallo, Afifa Imtiaz, & Donat Fäh

Submitted September 11, 2022, SCEC Contribution #12284, 2022 SCEC Annual Meeting Poster #228

Numerical modelling of strong ground motion is an essential part of understanding earthquake recordings and explaining processes that affect seismic wave propagation. Moreover, the prediction and modelling of strong ground motions is an important input for seismic hazard assessment in particular when considering long return periods as required for buildings of special importance like hospitals, dams, power plants, or nuclear facilities. Switzerland is a country characterized by moderate seismic hazard, although the risk can be significant due to potential damage and financial losses. As we are missing strong motion recordings in Switzerland, numerical modelling is necessary to characterize future potentially damaging earthquakes. In this preliminary study, we first aim at modelling broadband waveforms originating from regional, small-to-moderate (roughly 4≤Mw<5.5) earthquakes recorded in the Swiss Molasse basin. To achieve this, a numerical tool for simulating broadband waveforms is needed. We, therefore, use the SCEC hybrid broadband tool, which synthesizes low and high frequency waveforms and then combines them to obtain broadband waveforms.
The goal of our study is twofold: i) to validate the method and models based on existing recorded events and ii) to simulate scenario earthquakes for frequencies up to 40 Hz, if possible. Firstly, we perform broadband waveform modelling for validation purpose by using the Mw 4.1 Urnerboden earthquake that occurred in central Switzerland on 6th of March 2017. The modelling is done for specific seismic stations with their shear-wave velocity models inferred from site characterization measurements. The simulations will allow us to properly apply the tool by comparing the synthetics to the recorded waveforms in both temporal and spectral domains and assess their level of similarity in order to proceed to the second goal of our research. We intend to use the broadband tool to simulate scenario earthquakes (i.e. Mw=5.5-6.5) which could occur in the future. Such events are of particular interest for assessing the seismic hazard of locations where geological disposal facilities will potentially be constructed.

Key Words
Seismology, numerical modelling

Koroni, M., Hallo, M., Imtiaz, A., & Fäh, D. (2022, 09). Broadband waveform simulations of earthquake scenarios in the Swiss Molasse basin using the BBP tool from SCEC. Poster Presentation at 2022 SCEC Annual Meeting.

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Ground Motions