The 1998 Bovec‐Krn Mountain (Slovenia) Earthquake Sequence

Abstract

We study the 1998 Bovec‐Krn mountain (Slovenia) earthquake sequence by combining hypocenters relocation, strong motion inversion, digital elevation modelling and field geology. The main shock ( M s =5.7), a 12 km right lateral strike‐slip event on the Dinaric fault system, occurred on a sub‐vertical fault plane. The rupture, confined between 3 and 9 km depth, with no evidence of surface faulting, propagated bilaterally within two structural barriers. The northwestern barrier is at the junction between Dinaric and Alpine structures where there is a sharp change in the geometry of faulting. The southeastern barrier is within the Dinaric system and its surface expression corresponds to the Tolminka‐spring perched basin, a 1 km restraining step‐over. At this site, the Bovec‐Krn earthquake‐fault overlaps with a 30 km strike‐slip fault segment that is free of aftershocks and could be undergoing an increase of stress. This fault system represents the northern branch of the Idrija right‐lateral fault.