Kahramanmaraş Earthquake studies show potential slip rate errors

Accurate assessment of ground surface damage (such as small-scale destruction and inelastic deformation) from two major earthquakes in 2023 will allow scientists to assess the risks of future earthquakes and thus to the risks to people and infrastructure. It helps to minimize it. However, achieving accurate and broad measurements in seismic zones remains difficult.

The two earthquakes that hit on February 6th, 2023 were devastating. They were sized 7.8 and 7.6 and were immediately consecutively occurring near the Syrian and Turkish border. They caused extensive infrastructure destruction, leading to tens of thousands of deaths in multiple states.

Using two Kahramanmaraş earthquakes as a case study, Kaust researchers demonstrated that surface damage and inelastic deformation from the major faults are likely to be broadly expanded than previously thought.

The research paper has been published in the journal Nature Communications.

Jihong Liu, a postdoctoral researcher at Kaust’s crustal deformation and INSAR group, said, “The Kalaman Marash earthquake provided a unique opportunity to gain insight into the details of communal surface displacements in France. The results suggest that the width of the crustal damage zone reaches up to 5km from the fault itself, rather than hundreds of meters, as suggested in previous case studies.”

When two tectonic plates packed together move suddenly rather than steadily passing each other a few centimeters a year, a major earthquake occurs. This sudden slip, which brings meter-scale movement within seconds, causes extensive crustal damage. This damage is not only found near the plate boundary or fault, but also in “non-failure damage” (OFD) away from the main fault. Accurate measurement of OFD is an important factor in estimating fault slip rates and earthquake cycles, but most case studies of major earthquakes appear to significantly underestimate OFD.

The team used image data from synthetic aperture radar (SAR) satellites to quantify OFD and 3D surface displacements caused by two earthquakes. They used images taken before and after the two earthquakes.

“Radar satellites now transform seismic zone studies to allow us to visualize and analyze large areas of depth without the need for on-site observations,” says Liu.

Liu has developed the SM-VCE method, an advanced synesthetic 3D surface displacement measurement technique that the team used to accurately determine 3D motion, OFD, and surface deformation over a wide area around two earthquakes . They suggest that OFDs consume up to 35% of the communal displacement, and that slip rates in various regions of the world can be underestimated by a third. They also found that geometrically complex fault sections experience higher levels of OFD than simple linear faults.

“Our results affect geological measurements of fault slip velocity. If OFD is greater than previously thought, the plate boundary may move faster, causing larger earthquakes than expected. It means there is a possibility.” “This increases the estimated earthquake risk that has a serious impact on planned infrastructure, buildings and decision-making. Accurate OFD should also be considered in computer models of seismic zones.”

“To further verify and support the results of this study, we will perform OFD measurements on other typical earthquake incidents,” concludes Liu.