Communicating time-varying seismic risk during an earthquake sequence

• Autores: Marcus Herrmann, J. Douglas Zechar, Stefan Wiemer
• Localización: Seismological Research Letters, ISSN 0895-0695, ISSN-e 1938-2057, Vol. 87, Nº. 2 (A), 2016, págs. 301-312
• Idioma: inglés
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• Resumen

  • The 2009 L’Aquila event highlighted the importance of crisis communication and pushed the use of scientific methods to drive alternative risk mitigation strategies. For instance, van Stiphout et al. (2010) suggested a new approach for objective short‐term evacuation decisions: probabilistic risk forecasting combined with cost–benefit analysis. We apply this approach to a scenario earthquake sequence that simulated a repeat of the 1356 Basel earthquake, one of the most damaging events in central Europe. We analyze the simulated earthquake catalog and explore how we might provide decision support and information throughout such a crisis. Specifically, we describe a method that extends recent developments in short‐term seismicity forecasting and apply it to the Basel scenario. Compared with van Stiphout et al. (2010), we use an advanced aftershock forecasting model and more detailed settlement data to permit spatial forecasts and district‐wise decision making. With this method, we can make predictive statements about earthquake consequences, specifically quantified in terms of human loss. For instance 1 min after the simulated M 6.6 mainshock, the probability for an individual to die within the next 24 hours is four orders of magnitude higher than the long‐term average but remains far below 1%. The final cost–benefit analysis adds value beyond making probabilistic forecasts: it provides objective statements that may justify evacuations. We find that if a foreshock of M 5.5 or larger precedes the M 6.6 mainshock, evacuations in the central part of the city would be justified. To deliver supportive information in a simple form, we propose a warning approach in terms of alarm levels.