Unraveling the Preparatory Processes of the 2023 Kahramanmaraş Earthquake Doublet

Abstract

On February 6, 2023, within a span of 9 hours, two significant earthquakes of Mw7.8 and Mw7.6 struck the southeastern region of Turkey and northern Syria, resulting in substantial loss of life and extensive economic damage. These strong events occurred in an area where multiple tectonic plates converge, characterized by a complex fault system, presenting significant challenges in understanding their preparatory processes. To investigate whether the preparatory process of the Mw7.8-7.6 earthquake doublet could be identified at a large spatial scale prior to its occurrence, we focused on the b-value, a parameter with clear physical meaning in the magnitude-frequency relationship. We examined the migration pattern of the relative background value difference Δb before the earthquakes. In our study, we employed a data-driven approach for b-value calculation and the Cumulative Migration Pattern (CMP) method to quantitatively measure the migration pattern. The results indicate an overall decrease in b-values in the study area prior to the main-shock occurrence, signifying an evident enhancement of crustal differential stress. Noticeably, distinct migration patterns emerged near the epicenters before the earthquakes, revealing the preparatory process of the Mw7.8-7.6 earthquake doublet and potentially aiding in identifying the location of rupture nucleation points. These findings are expected to provide valuable scientific insights for the prevention of similar destructive earthquakes in the future.