Interseismic Strain Accumulation across the Main Recent Fault, SW Iran, from Sentinel-1 InSAR Observations

Abstract

The Main Recent Fault (MRF) is a 800 km long dextral stike-slip fault in the hinterlands of the Zagros mountains, Iran. The fault is one of the most seismically active in the northwestern Zagros, having experienced historical earthquakes up to M s 7.4 (Ambraseys & Moinfar, 1973;Ghods et al., 2012;Karasözen et al., 2019), driven by convergence between the Arabian and Eurasian plates. During the interseismic period of the earthquake cycle, the MRF can be viewed as accumulating strain in the locked upper crust whilst slipping aseismically at depth, following that assumed for other strike-slip fault zones (Savage, 2000;Savage & Prescott, 1978;Thatcher, 1983;Wright et al., 2013). Estimates of interseismic slip rate and the depth-extent of the locked seismogenic zone, from here on referred to as the "locking depth", are critical to our understanding of both the local seismic hazard (Smith-Konter & Sandwell, 2009), and the accommodation of oblique convergence across the Zagros. Previous studies of the MRF have used a range of geological markers, geomorphological offsets, cosmogenic isotope dating, and Global Navigation Satellite System (GNSS) measurements to estimate a wide range (1-17 mm/yr) of possible slip rates (Table 1). The average slip rates determined from long-term geological/geomorphological offsets (1

Earthquake Cycle Deformation Associated With the 2021 MW 7.4 Maduo (Eastern Tibet) Earthquake: An Intrablock Rupture Event on a Slow‐Slipping Fault From Sentinel‐1 InSAR and Teleseismic Data

“…Geodetically‐derived slip rates of major faults show, in general, agreement with geologic rates (W. Wang, Qiao, & Ding, 2021; Zheng et al., 2017), indicating that strain rates are basically steady through most of the earthquake cycle (Elliott et al., 2016) and that short‐term geodetic observations can directly make contributions to long‐term earthquake hazard assessment (Hussain et al., 2018; Wright, 2016). However, it is challenging to directly determine slip rates geodetically for faults with 1–2 mm/yr of slip or less (e.g., Calais & Stein, 2009; Newman et al., 1999; Smalley et al., 2005; S. Stein, 2007; Watson et al., 2022).…”

Mechanics of the Kalabagh Fault, northwest Himalayan fold and thrust belt (convergence zone of India and Eurasia), using SAR interferometry and CFS

“…In the context of InSAR processing, strain variations along the strike are often disregarded. However, this study demonstrates the potential for detecting such variations along faults using the extensive radar data archive provided by the Sentinel-1A satellite and applied an optimized processing approach that accounts for the reduction of atmospheric noise, similar to the Main Recent Fault in SW Iran (Watson et al, 2022). Despite this progress, limitations in our modeling persist, particularly regarding the simplified geometry and homogenous Earth crust.…”

“…For resolving the horizontal and vertical components of the approximately north-south KBF, fault plane and fault geometry are prerequisites to compute the strike-slip and dip-slip values. In order to do so, the following relation (Chen and Khan, 2010;Lindsey and Fialko, 2013;Watson et al, 2022) of slipping motion and LOS is adopted:…”