Characterizing Shallow Aseismic Deformation Along the Dead Sea Pull-Apart Basin Using Geodetic Observations

Abstract

We use creepmeter (CM), Global Navigation Satellite System (GNSS), Interferometric Synthetic Aperture Radar (InSAR) and airborne Light Detection and Ranging (LiDAR) observations to characterize transient aseismic deformation along the central Dead Sea pull-apart basin, which is located at the southern part of the sinistral Dead Sea Fault (DSF). A biaxial creepmeter was installed in early 2021 across a previously unmapped oblique-slip fault, measuring a combination of dip-slip and strike-slip, and providing the first evidence of creep events along the DSF. The creepmeter records predominantly normal faulting, at an average dip-slip creep rate of 22.2 mm/yr, among the highest in the world. This large rate is also evident with the ∼30 cm of subsidence recorded between 2017 and 2019 using differential LiDAR data. The data reveal seasonally variable dip-slip on the fault with a maximum rate of ∼0.5 μm/hr starting in August/September and approaching zero (mm/yr) in April. The creepmeter also records sinistral slip with an average rate of 1.3 mm/yr, about half of the total rate that was observed for the western side of the basin. Small Baseline Subset analysis of InSAR data indicate up to 13 mm/yr of line-of-sight displacement across the inferred fault. GNSS and InSAR data reveal high subsidence rate within the basin, between the western inferred fault and the Lisan salt diapir at the east and mostly along the shores of the lake. Our results indicate that deformation within the Dead Sea basin is not solely controlled by active tectonics. The observed vertical deformation is modulated by the thermo-elastic response of sediments and variations in local conditions, such as sediment compaction and fluid-pressure changes.