Abstract. This study uses interferometric SAR techniques to identify landslides and lands prone to landslides, detect fringes and changes in areas struck by earthquakes. The pilot study investigates the Mila region (Algeria) which suffered significant landslides and structural damages (earthquake: Mw 5, 2020-08-07): the study checks ground deformations and tracks earthquake-induced landslides. DInSAR analysis shows normal interferograms, with atmospheric contribution, and slight fringes. However, it identifies many landslides, the most important (2.5 m displacement) being located in Kherba neighborhood, causing severe damages to dwellings. In addition, SAR images and optical images (Sentinel-2) confirm site investigations. Although in Grarem City, optical images could not detect any disorder, the DInSAR analysis detected some coherence decays and small fringes (3.94 km2 area). These unnoticed ground disorders were confirmed during fields inspection. Such results have key importance since they can serve as an alert to monitor the zone at the proper time. Furthermore, Displacement time series analysis of many interferograms (April 2015 to September 2020) using LiCSBAS were performed to investigate the pre-event conditions and precursors of the slopes instabilities., LiCSBAS detects a line-of-sight subsidence velocity of −110 mm/y in the back hillside of Kherba, and high displacement velocity at specific points in Grarem region.

Abstract. This study uses interferometric synthetic aperture radar (SAR) techniques to identify and track earthquake-induced landslides as well as lands prone to landslides, by detecting deformations in areas struck by earthquakes. The pilot study area investigates the Mila region in Algeria, which suffered significant landslides and structural damage (earthquake: Mw 5, 7 August 2020). DInSAR analysis shows normal interferograms with small fringes. The coherence change detection (CCD) and DInSAR analysis were able to identify many landslides and ground deformations also confirmed by Sentinel-2 optical images and field inspection. The most important displacement (2.5 m), located in the Kherba neighborhood, caused severe damage to dwellings. It is worth notice that CCD and DInSAR are very useful since they were also able to identify ground cracks surrounding a large zone (3.94 km2 area) in Grarem City, whereas the Sentinel-2 optical images could not detect them. Although displacement time-series analysis of 224 interferograms (April 2015 to September 2020) performed using LiCSBAS did not detect any pre-event geotechnical precursors, the post-event analysis shows a 110 mm yr−1 subsidence velocity in the back hillside of Kherba.

A strong shaking with Mw7.3 occurred on Sunday November 12, 2017 around the Sarpol-e Zahab town in the border area between Iran and Iraq. It has a number of foreshocks and aftershocks increasing the total deformation, cumulatively. In this study, we have investigated how earth surface deformed after such a strong earthquake and its scatters. Because, the ground deformation inspection in some villages are indispensable for the safety of citizens and infrastructures. The best way for monitoring of surface deformation in such a big event is the SAR technique, which uses microwave signals. This system can work effectively during night and day under different weather conditions. The Interferometric SAR (InSAR) allows accurate measurements of surface deformations with the mm resolution. There are several methods for the application of SAR techniques and one of them is Differential InSAR (DInSAR) indicating an uplift and subsidence around epicentral area precisely and we preferred to use it for sensitive vertical displacement in the target area. The seismological data from the observatory centers indicate that the recent earthquake sourced from the NW-SE trending, northeast dipping High Zagros Reverse Fault Zone.According to the results of our analysis, epicentral area has been exposed a vertical displacement with 90 cm uplift and -41 cm subsidence in the northeastern and southwestern block of the fault, respectively.