Evolving architecture of a breached pull-apart basin: seismological constraints on the Kinneret Western Border Fault along the Dead Sea Fault

Basins along continental strike-slip plate-boundary fault systems, such as the N-trending Dead Sea Fault (DSF), are key sites of strain partitioning, where regional motion is accommodated by a variable combination of along-strike slip, across-fault shortening or extension, and vertical movements. The Sea of Galilee (Kinneret) basin developed along the DSF in three main tectonic stages: it was first hijacked from the predecessor NW-trending Irbid rift during the Early Miocene, then deepened and reorganized as a pull-apart basin during the Late Miocene–Pliocene while being filled by local sedimentation, marine incursions and extensive basaltic infill, and since the Early Pleistocene it has evolved into a breached basin, expressed today as a narrow, asymmetric E–W-trending syncline bounded by the Eastern Marginal Fault and the Kinneret Diagonal Fault within a generally transpressive DSF regime.

​Our new seismological analysis focuses on the mechanical behavior of the Kinneret Western Border Fault and its role in internal basin deformation. Using a high-resolution, relocated earthquake catalogue for 2018–2024 and Principal Component Analysis of hypocentral clusters, the study resolves active fault geometries and slip tendencies at unprecedented detail. Long-term seismicity aligns with the regional N–S tectonic grain (mean strike 187.5°, dip 59.2°), consistent with the broader DSF strike-slip kinematics, whereas the 2018 Sea of Galilee swarm activated a localized, rotated, low-angle bypass structure (strike 221.3°, dip 33.8°) that departs markedly from the conventional steep fault-plane models for the diagonal system. Existing tectonic models that infer a single, steeply dipping (~70°E) diagonal fault capture only part of the active structure; a nearly constant seismogenic thickness of ~150 m in both the long-term and swarm datasets indicates that the KWBF–diagonal system is better described as a volumetric damage zone rather than a discrete surface. These results demonstrate a structural decoupling between steady-state plate-boundary deformation and transient swarm dynamics and provide a new seismological framework for how evolving internal architectures of a breached pull-apart basin facilitate strain partitioning and ongoing development along the Dead Sea Fault.