Characterization and evolution of seismic sequences in the normal fault
environment of the Southern Apennines
Abstract
The use of seismic catalogs enhanced through advanced detection
techniques improves the understanding of earthquake processes by
illuminating the geometry and mechanics of fault systems. In this study,
we performed accurate hypocentral locations, source parameters
estimation and stress release modelling from deep catalogs of
microseismic sequences nucleating in the complex normal fault system of
the Southern Apennines (Italy). The application of advanced location
techniques resulted in the relocation of ~ 30% of the
earthquakes in the enhanced catalogs, with relocated hypocenters clearly
identifying local patches on kilometer-scale structures that feature
consistent orientation with the main faults of the area. When mapping
the stress change on the fault plane, the inter-event distance compared
to the size of the events suggests that the dominant triggering
mechanism within the sequences is static stress transfer. The
distribution of events is not isotropic but dominantly aligned along the
dip direction. These slip-dominated lineations could be associated with
striations related to fault roughness and could map the boundary between
locked and creeping domains in Apulian platform and basement.