From ground motion simulations to rockfall hazard scenarios: A look into cascading effects from the 2023 Turkish earthquakes

In the last decade the interest in understanding or assessing the susceptibility of earthquake induced landslides has considerably increased in the scientific literature. In this context rockfalls present a challenge due to the difficulty to collect information on fallen boulders following an earthquake emergency. The data obtained is often biased, as it is usually recorded only when it causes damage to buildings or road networks. Important aspects for future studies, such as the identification of source areas, are generally overlooked.

This study aims to develop a coseismic rockfall analysis based on the Turkish scenario, where two massive earthquakes of magnitude 7.8 and 7.5 struck on February 6, 2023, triggering approximately 3,673 landslides, the majority of which were rockfalls.  The approach combines data collection and statistical analysis to obtain the key input data needed for forecasting rockfall trajectories caused by future earthquakes.

The well-timed collection of post-event high resolution ortho-images allowed to realize a thorough coseismic rockfall inventory of the area affected by the earthquakes. This inventory will serve to train both the source area susceptibility model and the trajectories simulation model.

This information allows the application of an occurrence probability model based on ground motion predictive equations and the estimated peak ground acceleration for a potential earthquake along the left-lateral East Anatolian Fault, focusing on the identification of future source areas susceptible to rockfall. From these sources, some rockfall trajectories will be simulated to assess the hazard zonation along the main infrastructures like road, pipelines and villages.