3D Coseismic Deformation Field and Source Parameters of the 2017 Iran-Iraq Mw7.3 Earthquake Inferred from DInSAR and MAI Measurements

Zhiheng Wang,Yuxin Liu,Rui Zhang

doi:10.3390/rs11192248

Abstract

The coseismic slip on the main fault related to the 2017 Iran-Iraq Mw7.3 earthquake has been investigated by previous studies using DInSAR (differential interferometric synthetic aperture radar) ground deformation measurements. However, DInSAR observation is not sensitive to the ground deformation in the along-track (AT) direction. Therefore, only the one-dimensional (1D) DInSAR coseismic deformation field measurements, derived in the LOS (line-of-sight) direction of radar, was applied in source parameters estimation. To further improve the accuracy of the fault slip inversion, the 3D (three-dimensional) coseismic deformation fields were reconstructed in the first place, by a combined use of the DInSAR and MAI (multiple aperture InSAR) measurements. Subsequently, the LOS and 3D deformation data sets were used as the constraint respectively, to perform a two-step inversion scheme to find an optimal geometry and slip distribution on the main fault. The comparative analysis indicated that the 3D coseismic deformation data sets improved the inversion-accuracy by 30%. Besides, the fault invention results revealed a deep dislocation on a NNW trending fault (the strike is 352.63°) extending about 60 km, along the fault dips 14.76° to the ENE. The estimated seismic moment is 8.44 × 1019 Nm (Mw7.3), which is close to the solution provided by USGS (United States Geological Survey). The slip distributed at the depth between 12 and 18 km, and the peak slip of 6.53 m appears at the depth of 14.5 km left near the epicenter. Considering the geological structure in the earthquake region and fault source-parameters, it comes to a preliminary conclusion that the ZMFF (the Zagros Mountain Front fault) should be responsible for the earthquake. In general, this paper demonstrated the superiority of using the 3D coseismic deformation fields on source parameters estimation.

Highlights

The 2017 Mw7.3 Iran–Iraq Earthquake occurred in a region where the pattern of major plate convergence is well constrained (Figure 1)
This paper demonstrated the superiority of using the 3D coseismic deformation fields on source parameters estimation
The results demonstrate the advantage of 3D coseismic deformation fields in fault slip inversion

Summary

Introduction

The 2017 Mw7.3 Iran–Iraq Earthquake occurred in a region where the pattern of major plate convergence is well constrained (Figure 1). Networks Center)) published some source parameters [1,2,3,4,5,6,7], the variable slip on the main fault related with this earthquake is still uncertain. The ALOS-2 ScanSAR mode images were collected along both the ascending and descending orbit at a radar incidence angle of 39° in HH polarization and generated with a pixel spacing of 19.02 m in slant range and 25.9 m in azimuth (i.e., along track). 2019, the Senitnel-1A IW mode images were collected along both the ascending and descending orbits at radar incidence angle of 39.5° in VV polarization and generated with a pixel present detailed using the 20 m in azimuth.

Objectives

Methods

Results

Conclusion