Earthquake cycle simulations for seismic hazard assessment

Seismic hazard assessment (SHA) requires, among other components, a comprehensive representation of seismic sources that could affect sites or regions of interest, including their location and seismogenic character. Observational earthquake catalogs are generally too short or incomplete to provide a comprehensive source representation. Computer-generated earthquake catalogs, created by physics-based earthquake cycle simulations, can augment the observational catalogs, therefore contributing to improved SHA. With MCQsim, we developed an earthquake cycle simulator with this purpose in mind. MCQsim is openly available via GitHub. Since its initial publication in 2023, we were able to improve the code substantially, improving its performance and scalability, therefore enabling simulation for large-scale fault systems. Additionally, we built an interface between MCQsim and seismic hazard engine OpenQuake to streamline the incorporation of simulated catalogs into PSHA.

Here, we want to showcase these recent improvements. We perform earthquake cycle simulations for the Gulf of Aqaba and East Anatolian fault systems, creating earthquakes catalogs that span tens of thousands of years, with magnitude ranging from M3.5 to M7.8+. We validate these catalogs with observational constraints of the respective fault systems. Using these simulated catalogs, we investigate the occurrence of earthquake sequences, highlighting variations in large-earthquake occurrence probability as a function of time. We further showcase the integration of simulated catalogs into the OpenQuake environment, creating seismic hazard maps.