Co- and post-seismic slip analysis of the 2017 M_(W)7.3 Sarpol Zahab earthquake using Sentinel-1 data

The M_(w)7.3 Sarpol Zahab earthquake that occurred in the Zagros Fold-Thrust Belt(ZFTB) of Iran on November 12,2017 is the largest earthquake instrumentally recorded in the region.This earthquake provides an opportunity to investigate the slip behaviour and frictional properties of the fault,which is significant for assessing future seismic potential.In this study,we use Sentinel-1 images to map the coand post-seismic deformation to invert for the fault slip.The result indicates that most of the coseismic slip is buried in the depth range of 11-17 km,and the maximum slip is about 3.8 m at a depth of 15 km.The coseismic slip induces an increase of Coulomb stress in the unruptured area of the seismogenic fault plane,driving the afterslip.Based on the stress-driven afterslip,we obtain a frictional parameter of(ab)=(0.001-0.002) for the updip afterslip zone and(a-b)=0.0002 for the downdip afterslip zone in the framework of rate-and-state friction.The constitutive parameter(a-b) of the fault is very small,suggesting that the fault segments are close to velocity-neutral and may experience coseismic rupture.

Lessons learned from the Ezgeleh-Sarpol Zahab earthquake of November 2017:status of damage and disposal of disaster waste

A massive earthquake of magnitude Mw 7.3 shook Kermanshah Province in Western Iran along the Iraqi border on November 12,2017.The epicenter of the earthquake was approximately 10 km southwest of Ezgeleh Town in Kermanshah Province.Field observations almost 4 months after the disaster indicated that the earthquake had caused tremendous damage to most structures in both urban and rural areas,and left an enormous amount of disaster waste.To investigate the status of the dam-age and disposal of the disaster waste,remote sensing was conducted using an unmanned aerial vehicle(drone).Through the capture of low-altitude images by drone and the generation of 3D models,the quantity of debris accumulated in a waste disposal facility near Sarpol Zahab was estimated at approximately 480,000 m3.A compositional analysis of the disaster waste was performed using an imaging technique.This revealed that the disaster waste was largely composed of concrete(39.6%),hollow brick(35.4%),and gypsum(21.2%)in the urban area,whereas soil was the dominant component(77.4%)in the rural area.The damage caused to most buildings was essentially due to their non-standard construction.The manage-ment of debris from the damaged buildings was a critical issue for the authorities,and the lack of preparedness was a serious drawback that consumed an enormous amount of time,budget,and workforce.A practical post-disaster preparedness plan would help the decision-makers and the public to manage the otherwise overwhelming nature of the post-disaster conditions in a more reasonable manner.