Probabilistic and Deterministic Seismic Hazard Assessments for Northeast Algeria: Insights into the Damaging Impact of the August 7, 2020 (Mw 5.0) Mila Earthquake

This paper presents a comprehensive seismic hazard assessment of the Mila earthquake epicentral area that occurred on August 7, 2020 (Mw 5.0) in northeast Algeria. The analysis emphasizes the environmental factors that likely played a crucial role in amplifying the earthquake’s damaging impacts on the region. This interdisciplinary methodology encompasses several key aspects, including the earthquake catalog, an analysis of coseismic geological factors according to the environmental seismic intensity (ESI) scale, and the estimation of peak ground acceleration (PGA) values using both probabilistic and deterministic seismic hazard approaches (PSHA and DSHA, respectively). A comprehensive assessment of seismic intensity was conducted by examining primary and secondary impacts across three districts: El-Kherba, Grareme-Gouga, and Azzeba. Both PSHA and DSHA were conducted for the region, revealing that the varying intensity levels are linked to the distributions of modified mercalli intensity (MMI) and PGA. Our findings show that the hazard estimation methods used can result in significant variations in the PGA distributions. Moreover, PGA values often diverge significantly from macroseismic intensity levels derived using the ESI scale. Consequently, incorporating environmental factors into hazard assessments is essential for achieving a more accurate seismic evaluation. In the final phase, seismic hazard assessment methods are employed to estimate damage distributions at risky locations, considering a 50-year exposure period. The results show the importance of taking precautions to reduce earthquake casualties in vulnerable old urban centers. This work proposes a methodology for conducting site-specific hazard and vulnerability estimations to mitigate earthquake hazard and support risk reduction measures.