The relationship between global plate motion and intra-plate deformation analysis of Cairo network: case study with simulated data

Abstract

Although the Cairo region is classified as a low and moderate seismological area, the frequent earthquakes (M = 2-4) and the largest one at 12th October 1992 (M = 5.9) prove the recent seismotectonic activity of the area, which is connected to the known fault systems. To monitor the tectonic changes, GPS network was established in Cairo region and analyzed between 1986 and 2003. Because of technical reasons, the network was updated in 2011 and the data processing methods were reconsidered. The application of usual methods require a very careful approach since the Cairo network is very fare from the known fiducial GPS stations at the African plate, the nearer fiducial stations are at different plates, and the network is near to the plate borders. For the investigation of these circumstances, UNAVCO plate motion calculator was used to simulate coordinate changes, and the impact of the chosen plate motion on the result of intra-plate deformation monitoring was analyzed. New data processing approach and integrated baseline adjustment and similarity transformation method is proposed as an alternative strategy for the regional size Cairo network to estimate intra-plate deformations using GPS observations. The proposed method is demonstrated to estimate coordinate changes, global rotations, and scale parameters in one computational step. The proposed method is used to investigate the significance of the impact of global plate motions on regional crustal movement network. Simulated data of the regional Cairo network is used for this evaluation. The estimated plate motions, simulated scale bias (due to miss-modeling of troposphere effect on GPS data) and baseline noise proved that the impact of plate motions have to be taken into account in the case of Cairo network if the investigation period is near or larger than 10 years.