Analyzing InSAR time series: Case study on salt diapir intrusions and sabkhas in Southwestern Saudi Arabia
Abstract
Jazan City, capital of the Jazan province, is a growing port city (area: year 1984, 24 km2; year 2018, 80 km2) within the Red Sea coastal plain in southwest Saudi Arabia. Constructional and infrastructural problems have been continuously reported from this area. We conducted radar interferometric studies to identify the nature and distribution of the reported deformation and to provide guidance for further development of the city and its surroundings. Persistent Scatterer Interferometry (PSI) and Small BAseline Subset (SBAS) techniques were applied to ESA's Envisat (7 scenes) and Sentinel-1 (83 ascending and 89 descending scenes) C-band radar images covering a temporal time span of ~16 years. Descending Envisat scenes were processed using Stanford Method for Persistent Scatterers (StaMPS), and both ascending and descending modes of Sentinel-1 scenes were processed in SARscape. InSAR trials involved varying one or more of these parameters: number of scenes, coherence threshold, and atmospheric phase screening window size. Velocity results from both satellites were compared against (1) high-resolution TanDEM-X DEM (12 m) for isolated uplifted areas, (2) continuous GPS measurements to constrain the velocity results, (3) and band-ratio images of Worldview-3 (16-band) superspectral satellite highlighting areas of exposed cap rock and sabkhas. Findings include: (1) concurrent uplift and subsidence is occurring in and around the Jazan city, (2) the uplift is largely caused by a salt diapir (area: ~ 1.5 km2) that intruded the overburden sediments, whereas subsidence was observed mainly over sabkhas, (3) five areas (areas ranging from 0.2 to 0.6 km2) undergoing uplift (2 to 4 mm/yr; average: ~3 mm/yr) were identified in the immediate surrounding the dome outcrop, and (4) four areas (areas ranging from 0.6 to 2 km2) distant (0.5 to 5 km) from the dome are witnessing subsidence (-3 to -8 mm/yr; average: ~5 to 6 mm/yr). The uplift in and around the salt diapir is interpreted as being related to the continuous rise of the diapir, and the subsidence is from the settlement of back-filled materials and compaction over the sabkhas. Field checks will be conducted to investigate the integrity of buildings and infrastructures within the identified uplift and subsidence areas.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.G11B0525P
- Keywords:
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- 1209 Tectonic deformation;
- GEODESY AND GRAVITY;
- 1211 Non-tectonic deformation;
- GEODESY AND GRAVITY;
- 1240 Satellite geodesy: results;
- GEODESY AND GRAVITY;
- 1241 Satellite geodesy: technical issues;
- GEODESY AND GRAVITY