Updated Determination of Earthquake Magnitudes at the Swiss Seismological Service

Session: Regional Earthquake Centers: Highlights and Challenges [Poster]
Type: Poster
Date: 4/28/2020
Time: 08:00 AM
Room: Ballroom
Description: 

The Swiss Seismological Service (SED; http://www.seismo.ethz.ch) at ETH Zürich is the federal agency in charge of monitoring earthquakes in Switzerland and for the assessment of seismic hazard and risk for the region. The SED seismic network activites, event alerting and web infrastructure mostly rely on software and databases integrated in SeisComP3 (SC3) for waveform acquisition, automatic / manual event processing, data archiving / dissemination. Data from all digital stations acquired by the SED - broadband (presently ~230), strong-motion (~185), short-period (~65), permanent and temporary - are homogeneously integrated in the seismic network processing tools and products. Waveform (meta)data from the Swiss National Seismic Networks are openly available via the SED website and ORFEUS EIDA / SM (http://orfeus-eu.org/data/) data gateways. The SED quake catalogue is openly accessible through FDSN Event webservices at http://arclink.ethz.ch/fdsnws/event/1/. The Swiss seismic hazard maps are integrated in EFEHR (http://www.efehr.org). The SED is updating its strategy for magnitude determination to make it fully consistent with current engineering seismology and seismic hazard studies in Switzerland and to optimise the use of its dense seismic monitoring infrastructure. Among the changes are the: (a) adoption of a new ML equation applicable in the near-field at epicentral distances < 15-20 km; (b) inclusion of ML station corrections based on observed (de)amplification with respect to the Swiss reference rock velocity model and associated ground-motion predictions; (c) seamless computation of Mw based on spectral fitting of recorded FAS using a Swiss specific model. In this contribution we present and discuss the updated magnitude computations for a playback dataset of thousands of recorded earthquakes and compare them with the current official estimates. We discuss the expected impacts of the new magnitude values on the SED event processing chain in SC3, the SED catalogues and other seismological products. We welcome community feedback on our planned transition strategy.

Presenting Author: Carlo Cauzzi

Authors