PRISM - Probabilistic Inference of Source Mechanisms

• Applicant: Dr. Simon Stähler
• Subject Area: Geophysics
• Term: from 2017 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 336226956

How much does our limited knowledge about earthquakes affect the whole seismological effort? This project aims at quantifying the limits of knowledge about earthquakes, the seismic sources. It aims at rigorously estimating the uncertainty of seismic source solutions using Bayesian Inference for intermediate size earthquakes (magnitude > 5.5) globally. The results will be shared with the geoscientific community in form of a global probabilistic earthquake catalogue.Since earthquakes are used to infer properties of the system earth in almost all solid earth geosciences, the uncertainty of source solutions propagates into many other disciplines. This is the case, where earthquakes are used directly, e.g. to constrain the tectonic regime of a region, but also indirectly, as in seismic tomography, where earthquakes are used as powerful sound sources to image the deep interior of the Earth. Compared to existing catalogues, PRISM will contain results in form of probability density functions as well as an estimate of the temporal evolution of the earthquake, the so-called Source Time Function. This will foster research about scaling of rupture size and duration and thereby the nature of fault rupture propagation. An open dataset including uncertainties of source parameters will have an effect on a range of other fields, such as seismic hazard mapping or tectonic interpretation. As a primary application, the influence of source uncertainty on seismic tomography shall be shown. This method that is strongly hindered by uncertainty in the source parameters. The effect of source uncertainties on these results was hitherto unknown and shall be quantified. To this end, two frequency-dependent travel-time datasets (Europe and Northern America) will be used with the method of waveform tomography. Additionally, international cooperators will use the catalogue to determine the effect of uncertainties on parameters as the stress drop. During and after the project, the resulting catalogue will be available for the whole geoscientific community.

• DFG Programme: Research Grants
• International Connection: France, United Kingdom
• Co-Investigators: Professor Dr. Torsten Dahm; Professor Dr. Frank Krüger
• Cooperation Partners: Professorin Dr. Karin Sigloch; Martin Vallée