Application of Sentinel-1 and-2 Images in Measuring the Deformation of Kuh-e-Namak (Dashti) Namakier, Iran

Sen Zhang,Qigang Jiang,Yundi Gong,Bin Liu,Jing Xi,Xitong Xu,Wenxuan Liu,Chao Shi

doi:10.3390/rs13040785

Abstract

Kuh-e-Namak (Dashti) namakier is one of the most active salt diapirs along the Zagros fold–thrust belt in Iran. Its surface deformation should be measured to estimate its long-term kinematics. Ten Sentinel-2 optical images acquired between October 2016 and December 2019 were processed by using Co-Registration of Optically Sensed Images and Correlation (COSI-Corr) method. Forty-seven Sentinel-1 ascending Synthetic Aperture Radar (SAR) images acquired between April 2017 and December 2019 were processed by using Small Baseline Subset Synthetic Aperture Radar Interferometry (SBAS-InSAR) method. The deformation of Kuh-e-Namak (Dashti) namakier was measured using both methods. Then, meteorological data were utilized to explore the relationship between the kinematics of the namakier and weather conditions and differences in macrodeformation behavior of various rock salt types. The advantages and disadvantages of COSI-Corr and SBAS-InSAR methods in measuring the deformation of the namakier were compared. The results show that: (1) The flank subsides in the dry season and uplifts in the rainy season, whereas the dome subsides in the rainy season and uplifts in the dry season. Under extreme rainfall conditions, the namakier experiences permanent plastic deformation. (2) The “dirty” rock salt of the namakier is more prone to flow than the “clean” rock salt in terms of macrodeformation behavior. (3) In the exploration of the kinematics of the namakier via the two methods, COSI-Corr is superior to SBAS-InSAR on a spatial scale, but the latter is superior to the former on a time scale.

Highlights

Rock salt is one of the few rocks that can flow
SBAS-Interferometric Synthetic Aperture Radar (InSAR) method is not limited by the sun zenith angle
On the basis of Sentinel-1 and-2 images, the kinematics of Kuh-e-Namak (Dashti) namakier was efficiently measured through COSI-Corr and SBAS-InSAR methods

Summary

Introduction

Rock salt is one of the few rocks that can flow. As a conventional element of the oil and gas system, rock salt is vital to the evolution of trap structures and the formation of oil and gas migration paths [1,2]. Storage caverns can be excavated in salt diapirs to store energy or hazardous chemical and nuclear waste materials because rock salt has the characteristics of creep, good sealing, and self-deformation recovery [3]. Exposed salts diapirs in the Zagros fold–thrust belt and central Iran between Alborz. Kuh-e-Namak (Dashti) namakier is located between Dashti and Dayyer counties in Bushehr Province in Iran (Figure 1a). The namakier is composed of the Hormuz Formation rock salt, which consists of Infra-Cambrian and Cambrian evaporites with an original thickness of about 1–2.5 km [35]. Around the Miocene, as the Arabian and Central Iranian plates continued to expand and squeeze along the main Zagros fault, rock salt continued to rise and spread around to form the namakier [36]. Namak (Dashti) namakier (modified from [37]).

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Conclusion