Recent ground deformation around lake Nasser using GPS and InSAR, Aswan, Egypt

Abstract

The rate of seismic activity around lake Nasser rapidly increased after the creation of the High Dam. The largest earthquake was of magnitude ML 5.6 ; it occurred on November 14th 1981, 60 km southwest of the Aswan High Dam. We use 16 years of GPS measurements collected around the northern part of lake Nasser, represented by 27 GPS sites, plus eight years of Envisat SAR scenes, 35 descending scenes, to estimate the recent ground movement of this area. GPS and InSAR showed a land subsidence localized around lake Nasser. The subsidence has a magnitude of 1–2 mm/yr. Therefore, we model the Earth's response to water level changes, using full daily water level variations starting from 1982 to 2016. Our loading model captures a similar deformation pattern, like ones estimated from GPS and InSAR, around the lake with comparable amplitudes. With respect to stable Nubia, most of GPS sites around the lake show a negligible North to Northeast motion of <1 mm/yr. Along Kalabsha fault, we estimate a strike-slip motion with an extension component of 0.6 mm/yr. GPS sites around Sayal fault do not show any differential motion along the fault in both fault-parallel and fault-normal components. The InSAR result would not be able to capture the deformation at Kalabsha and Sayal region, since the deformation in this area is <1 mm/yr.