Retrieving North-South Dextral Shear with SAR Azimuth Offsets: The West-Lut Fault in Eastern Iran
Abstract
Measurements of the global strain earthquake is increasingly being accomplished using the space-based geodetic technique of InSAR. However, a major limitation in the use of this technique, especially compared to those from other methods such as GNSS, is the polar orbiting nature of SAR platforms, and consequently the relative down and east-west look direction of the sensors. This restriction commonly results in sensitivity of surface motion that is greatest in the vertical and east-west directions, with much less constraint on north-south motion. Therefore, past studies have often neglected major strike-slip faults that are accumulating significant tectonic strain, but are sub-optimally orientated in the north-south direction. However, with the launch of Sentinel-1A in 2014 making regular acquisitions and having its particular mode of SAR retrieval using multiple bursts, it is possible to use a spectral diversity technique to determine offsets in the azimuth (north-south) direction with greater sensitivity than previously possible. Although this azimuth offset technique has been proven to accurately extract large displacement in the north-south direction, such as from earthquakes, the technique is still limited in its measurements of surface displacements associated with interseismic deformation in regions that are relatively low-straining. This is because there is a significant effect from the ionosphere as well as decorrelation noise resulting from longer period interferograms. Here, we employ 33 SAR images in the period 2014-2017 from the Sentinel-1 constellation across the West-Lut Fault in Eastern Iran. This is a predominately north-south striking fault that is known to be active, accumulating approximately 4 mm/yr of right lateral slip across it. The result from time-series azimuth offset analysis with the mitigation for the ionospheric effect shows the right-lateral motion of the fault and the velocity is similar to a previous GPS data study. With the ability to retrieve the north-south component independently, this work presents the first steps that will enable the full three components of deformation for tectonics to be retrieved from ascending and descending Sentinel-1 satellites, even for relatively small deformation signals.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.G23C0610P
- Keywords:
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- 1209 Tectonic deformation;
- GEODESY AND GRAVITYDE: 3040 Plate tectonics;
- MARINE GEOLOGY AND GEOPHYSICSDE: 7230 Seismicity and tectonics;
- SEISMOLOGYDE: 8107 Continental neotectonics;
- TECTONOPHYSICS