Quake4D renewal project

Earthquakes cannot currently be predicted and therefore we rely on probabilistic seismic hazard assessment (PSHA) to assess the likelihood that an earthquake will occur over a specified period of time. Seismic hazard assessment is usually based on short-term observations, for example where and how many earthquakes occurred in the last few decades, and key assumptions, for example that earthquakes occur randomly and independently. This is a problematic approach because it is well established that the recurrence times of individual damaging earthquakes may be hundreds or even thousands of years (i.e. far longer than the instrumentally earthquake catalogue), and that earthquakes are known to cluster both temporally and spatially (i.e. they are not random or independent). Therefore, different approaches to characterising the sources and frequency of earthquakes need to be explored. During my FLF to date, we have explored how fault slip rates change over much longer timescales than previously considered by the seismic hazard community, giving insights into how faults interact and accommodation tectonic strain, and we have developed a new method to produce seismic hazard maps using physics-based numerical modelling, driven by field data, to generate synthetic earthquake catalogues over longer time periods (10-20kyrs). In this proposed UKRI FLF renewal project, the work will focus on a new study region (central Greece) and will explore how variable fault behaviour over a wide range of timescales would affect seismic hazard assessment. Central Greece is a region of active extension, with well exposed and studied normal faults. These faults are documented to behave variably, particularly in relation to variable slip/deformation rates, from timescales stretching from years to hundreds of thousands of years. The overarching aim of the proposed project is to apply earthquake cycle modelling (developed in the Quake4D project to date) and explore how seismic hazard varies over time. The key objectives of the project are: Quantify annual-scale deformation across an active normal fault using InSAR. Enhancing and creating a database of active fault data for seismic hazard models Further develop physics-based earthquake cycle modelling using multiple normal faults and documented variable slip rates over thousands to hundreds of thousands of years. Produce a suite of seismic hazard maps to gain insights into pitfalls of probabilistic seismic hazard assessment and the potential for calculating time dependent seismic hazard. This project will advance our scientific understanding in two key areas, 1) how faults behave over short timescales and the physical mechanisms of the earthquake cycle, and 2) how variable seismic hazard can be resulting from variable fault behaviour over a range of timescales, giving insights into time-dependent seismic hazard. These results will be of interest to both the academic community studying active tectonics, but also the risk industry, catastrophe modellers and the government and local populations of areas affected by earthquakes.