Static stress changes due to the 1998 and 2004 Krn Mountain (Slovenia) earthquakes and implications for future seismicity

Abstract. In this paper we examine the Coulomb (static) stress pattern following the two moderate magnitude earthquakes in NW Slovenia during 1998 and 2004. These earthquakes ruptured patches of the NW-SE striking Ravne fault that crosses the Krn Mountain. The objective is to investigate the seismicity patterns for this area of Slovenia given that future earthquakes may be triggered as a result of stress changes along neighbouring faults. Our findings include: a) stress levels have increased along the active Ravne fault for all models discussed b) stress levels have decreased along the active, NW-SE striking Idrija fault and c) stress levels throughout the crust have increased along the E-W direction but have decreased in the N-S direction (stress shadow effect). We also mapped a better correlation of the off-fault aftershock locations with stress maps incorporating the regional stress field.