Virtual Lower Rhine Embayement: Physics-based numerical simulation of earthquake ruptures and seismic cycles

• Antragsteller: Privatdozent Dr. Sebastian Hainzl
• Fachliche Zuordnung: Physik des Erdkörpers
• Förderung: Förderung von 2008 bis 2013
• Projektkennung: Deutsche Forschungsgemeinschaft (DFG) - Projektnummer 68175803

• Erstellungsjahr: 2013

Zusammenfassung der Projektergebnisse

The occurrence of earthquakes in populated areas can produce enormous damage in terms of fatalities and economic loss. Knowledge of earthquake occurrence probabilities at a specific site is therefore crucial for purposes of preparedness and risk mitigation. This includes three steps: (1) design of data-driven models for earthquake occurrence, (2) calculation of the ground motion hazard, and (3) estimation of the seismic risk (hazard × loss potential). The first step is delicate in regions with overall low seismic activity, but high risk potential. The Lower Rhine Embayment in Germany experienced earthquakes in 1756 (Düren, moment magnitude mw = 5.4) and 1992 (Roermond, mw = 5.2); paleoseismological studies indicate, however, magnitudes around 6.7. As a first result of this project, we showed that based on statistical analysis of historic seismicity, earthquakes with even higher magnitudes have to be considered in the Lower Rhine Embayment. Next, we designed a numerically efficient model framework to generate “synthetic earthquakes” in this region for time periods of thousands to millions of years based on laboratory-derived friction laws and realistic stress interactions between fault segments. This allows to overcome the problem of sparse and incomplete data: occurrence probabilities of earthquakes with arbitrary magnitude can be calculated in straightforward fashion. The model framework enables us to perform various scenario calculations for seismicity evolution and evaluate the results on statistical robust grounds. A main challenge of the project was the estimation and evaluation of model uncertainties, i.e. addressing the question: how sensitive is the generated seismicity on the details of the model assumptions? Here we obtained the surprising result that for isolated faults, the physics of complex, high-dimensional, interacting fault portions can be plugged easily into a stochastic component without loosing significant information. Although this result does not hold for a system of faults, it is promising to model the system by isolated faults and introduce an effective fault coupling term instead of simulating the full 3D dynamics. The results of the project have clearly potential for applications of seismic hazard and risk analysis. After selecting the best model from the available model framework, the synthetic catalogs can be used for calculating the ground motion hazard in the Lower Rhine Embayment. The combination with vulnerability data will offer the opportunity to improve seismic risk estimations. Finally, we note that the statistical studies on maximum magnitudes have initiated further case studies, e.g. in relation to the M9 Tohoku earthquake that occurred during the project period.

Projektbezogene Publikationen (Auswahl)

• Quantitative earthquake forecasts resulting from static stress triggering, Journal of Geophysical Research, 115, B11311
  Hainzl, S., Brietzke, G. B., and Zöller, G.
  
• Recurrence of large earthquakes: Bayesian inference from catalogs in the presence of magnitude uncertainties, Pure and Applied Geophysics
  Zöller, G., Hainzl, S., and Holschneider, M.
  
• Seismicity models based on Coulomb stress calculations, Community Online Resource for Statistical Seismicity Analysis
  Hainzl, S., Steacy, S., and Marsan, D.
  
• Steady-state solutions of rupture propagation in an earthquake simulator governed by rate and state dependent friction, The European Physical Journal Special Topics, 191, 105-115
  Zöller, G., Hainzl, S., Holschneider, M., and Brietzke, G.
  
• A multigrid solver for modeling complex interseismic stress fields, Computers & Geosciences, 37(8), 1075-1082
  Shin, S., Z¨ller, G., Holschneider, M., and Reich, S.
  
• Basic models of seismicity: Spatiotemporal models, Community Online Resource for Statistical Seismicity Analysis
  Zhuang, J., Werner, M. J., Hainzl, S., Harte, D., and Zhou, S.
  
• Estimation of the maximum possible magnitude in the framework of the doubly-truncated Gutenberg-Richter model, Bulletin of the Seismological Society of America, 101(4), 1649-1659
  Holschneider, M., Zöller, G., and Hainzl, S.
  
• Comparison of deterministic and stochastic earthquake simulators for fault interactions in the Lower Rhine Embayment, Germany, Geophysical Journal International, 195, 684694
  Hainzl, S., Zöller, G., Brietzke, G. B., and Hinzen, K.-G.
  
• The maximum earthquake magnitude in a time horizon: Theory and case studies, Bulletin of the Seismological Society of America, 103 (2A), 860-875
  Zöller, G., Holschneider, M., and Hainzl, S.