After an earthquake event, major ground effects include landslides. In Italy, the most common type of earthquake-induced landslides are rockfalls. The assessment of the extent and magnitude of an earthquake-induced landslide event may be of importance for both preparedness and response operations. An earlier work devised a modeling chain including an empirical ground shaking scenario and a three-dimensional model for rockfalls, which can be calibrated and possibly applied in real time after an earthquake event. In this study, we explore the combined use of two physics-based methods for both earthquake and rockfall modeling and their possible contribution towards a better understanding of the triggering mechanisms and characterization of seismically induced rockfalls. Specifically, by modeling a set of ground shaking scenarios, which account for increasingly complex details (including multiple seismic events, as well as point and extended sources) and the related rockfall scenarios, we aim to capture the main spatial patterns of observed rockfalls. Application of the proposed modeling chain suggests an advantage of using multiple sources over a single source, and point sources with respect to approximate extended representations when constrained by limited available data. This follows from the comparison of rockfall trajectory simulations for the Friuli 1976 event in Northern Italy with observed rockfalls induced by the seismic sequence. The obtained results evidence the opportunity of including topographic effects in the ground shaking simulations and highlights the possibility of further investigating the cumulative effect of complex seismic sequences and their influence on modulating landslide susceptibility.

The available historical documents for the city of Alexandria indicate that it was damaged to varying degrees by several (historical and instrumentally recorded) earthquakes and by highly destructive tsunamis reported at some places along the Mediterranean coast. In this work, we applied the neo-deterministic seismic hazard analysis (NDSHA) approach to the Alexandria metropolitan area, estimating ground motion intensity parameters, e.g., peak ground displacement (PGD), peak ground velocity (PGV), peak ground acceleration (PGA), and spectral response, at selected rock sites. The results of this NDSHA zonation at a subregional/urban scale, which can be directly used as seismic input for engineering analysis, indicate a relatively high seismic hazard in the Alexandria region (e.g., 0.15 g), and they can provide an essential knowledge base for detailed and comprehensive seismic microzonation studies at an urban scale. Additionally, we established detailed tsunami hazard inundation maps for Alexandria Governorate based on empirical relations and considering various Manning’s Roughness Coefficients. Across all the considered scenarios, the average estimated time of arrival (ETA) of tsunami waves for Alexandria was 75–80 min. According to this study, the most affected sites in Alexandria are those belonging to the districts of Al Gomrok and Al Montazah. The west of the city, called Al Sahel Al Shamally, is less affected than the east, as it is protected by a carbonate ridge parallel to the coastline. Finally, we emphasize the direct applicability of our study to urban planning and risk management in Alexandria. Our study can contribute to identifying vulnerable areas, prioritizing mitigation measures, informing land-use planning and building codes, and enhancing multi-hazard risk analysis and early warning systems.