The mechanical behaviour of large faults presents a fundamental paradox: geophysical evidence suggests they are weak but produce significant coseismic stress drops without the predicted interseismic strain localization. Moreover, earthquake recurrence is clustered and irregular, suggesting residual strain may persist between cycles, as proposed by long-term fault memory models. However, friction during slip is extremely low and near-complete stress drops imply negligible residual strain should survive. Observations of loosely slip-predictable earthquakes further challenge elastic rebound models. Here, I propose that faults are ‘short-sighted’: tectonic stress is partially screened by adjacent anelastic zones. Using a Burgers rheology model, I identify four different temporal regimes governing stress evolution. Stress initially accumulates within the screening zone and progressively transfers toward the fault. This mechanism reconciles observed coseismic stress drops with broadly distributed interseismic strain and physically explains the irregular recurrence of large earthquakes and long-term crustal memory, with implications for seismic hazard assessment.
Short‐sighted faults. A new model for earthquake recurrence and crustal memory / Zaccagnino, Davide. - In: TERRA NOVA. - ISSN 0954-4879. - (2026). [10.1111/ter.70036]
Short‐sighted faults. A new model for earthquake recurrence and crustal memory
Zaccagnino, Davide
Primo
2026
Abstract
The mechanical behaviour of large faults presents a fundamental paradox: geophysical evidence suggests they are weak but produce significant coseismic stress drops without the predicted interseismic strain localization. Moreover, earthquake recurrence is clustered and irregular, suggesting residual strain may persist between cycles, as proposed by long-term fault memory models. However, friction during slip is extremely low and near-complete stress drops imply negligible residual strain should survive. Observations of loosely slip-predictable earthquakes further challenge elastic rebound models. Here, I propose that faults are ‘short-sighted’: tectonic stress is partially screened by adjacent anelastic zones. Using a Burgers rheology model, I identify four different temporal regimes governing stress evolution. Stress initially accumulates within the screening zone and progressively transfers toward the fault. This mechanism reconciles observed coseismic stress drops with broadly distributed interseismic strain and physically explains the irregular recurrence of large earthquakes and long-term crustal memory, with implications for seismic hazard assessment.| File | Dimensione | Formato | |
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