A Millennial Perspective on Coulomb Stress Transfer Impact in the seismicity of the Central Apennine Fault System

This research examines the influence of static Coulomb Stress Transfer (CST) in shaping the seismic cycles associated with the Central Apennine Fault System (CAFS), an active tectonic region that witnessed numerous destructive seismic events over the last millennium.

We selected 15 seismic events in the CAFS, dating from 1279 CE to the present, all exceeding Mw 6.0. Out of these, 9 events were specifically chosen for CST analysis, based on their spatial-temporal proximity to later activated faults. The study not only investigates static stress transfer for each event, but also considers the cumulative CST from recent earthquakes, providing a holistic view of the current stress environment. Following a novel approach, we utilized a three-dimensional fault modeling technique, with ellipses representing the 2D geometry of faults at depth. This approach accounts for strike variations and employs a variable strike three-dimensional elliptical model for enhanced precision in CST calculations.

Our case studies within the CAFS suggest that CST might have been a critical factor in either triggering or inhibiting fault activities. Instances of fault reactivation following high stress transfers and scenarios showing the dampening effects of stress shadows were observed. This intricate understanding of CST has practical implications, offering insights into potential future earthquake patterns and aiding in devising targeted risk mitigation strategies.

The complexity of CAFS reveals intricate stress patterns emerging from the interplay of different seismic episodes. These patterns of stress lobes interact in complex ways, influencing adjacent faults by amplifying, neutralizing, or diversifying their CST impacts. Through detailed analyses and cutting-edge modeling techniques, our study provides valuable insights for future research directions and practical approaches to seismic risk reduction. It underscores the strong impact of CST on shaping a region's seismic history and highlights the necessity of ongoing research in this vital area of geosciences.