Gas escape along the Palmachim disturbance in the Levant Basin, offshore Israel

High-resolution seismic reflection and bathymetry data are analyzed to investigate the subsurface configurations promoting fluid escape along the Palmachim disturbance; a 20 km × 10 km gravitational collapse structure, offshore southern Israel. The dataset reveals seabed pockmarks with diameters ranging between 200 and 500 m, and depth of <50 m. A significant number of the pockmarks are located along ridge-like structures associated with compression, while an outlier is proximal to a turbidite channel. Seismic attribute analyses reveal a series of fluid-related amplitude anomalies within Quaternary sediments. We propose the onset of subsurface fluid flow to be synchronous with the evolution of the Palmachim disturbance, which was likely triggered by local seismicity. Our results suggest fluids from pre-Messinian strata exploited deformational pathways in the overburden to reach shallower levels where they were sequestered and redistributed in transient reservoirs (mass-transport complexes and channel-levee complex). The fluids are either focused toward the seafloor for expulsion or migrating into the ridges, providing four-way closure and accommodation. However, the fluids may also have no (pre)Messinian component, being locally sourced biogenic methane within the channel-levee complex. Under both scenarios, elevated pore-pressure resulted in hydrofracturing of the seafloor sediment and expulsion of fluids creating the pockmarks. The discovery of enhanced fluid escape through the Palmachim disturbance represents a new source of global methane not previously accounted for in carbon budgets from this region of the Mediterranean Sea.