Deformation and Related Slip Due to the 2011 Van Earthquake (Turkey) Sequence Imaged by SAR Data and Numerical Modeling

Abstract

A Mw 7.1 earthquake struck the Eastern Anatolia, near the city of Van (Turkey), on 23 October 2011. We investigated the coseismic surface displacements using the InSAR technique, exploiting adjacent ENVISAT tracks and COSMO-SkyMed images. Multi aperture interferometry was also applied, measuring ground displacements in the azimuth direction. We solved for the fault geometry and mechanism, and we inverted the slip distribution employing a numerical forward model that includes the available regional structural data. Results show a horizontally elongated high slip area (7-9 m) at 12-17 km depth, while the upper part of the fault results unruptured, enhancing its seismogenic potential. We also investigated the post-seismic phase acquiring most of the available COSMO-SkyMed, ENVISAT and TERRASAR-X SAR images. The computed afterslip distributions show that the shallow section of the fault underwent considerable aseismic slip during the early days after the mainshock, of tens of centimeters. Our results support the hypothesis of a seismogenic potential reduction within the first 8-10 km of the fault through the energy release during the post-seismic phase. Despite non-optimal data coverage and coherence issues, we demonstrate that useful information about the Van earthquake could still be retrieved from SAR data through detailed analysis.

Coeval Uplift and Subsidence Reveal Magma Recharging Near Rome (Italy)

“…Local tomography by Chiarabba et al () evidenced localized velocity anomalies up to 20% shallower than 6 km depth. The effect of such anomalies may be considered negligible since the ensuing deformation field at surface would be similar to that obtained with homogeneous models (Masterlark, ; Trasatti et al, ). More in general, this also applies to cases with only large‐scale characterization of the lithosphere and limited knowledge of the local heterogeneities.…”

Spatial Relationships Between Coseismic Slip, Aseismic Afterslip, and On‐Fault Aftershock Density in Continental Earthquakes

“…Afterslip mostly occurred in the top ∼10 km (Dogan et al, 2014;Trasatti et al, 2016;, above most of the coseismic slip (Elliott et al, 2013;Fielding et al, 2013;Konca, 2015;Mackenzie et al, 2016;. We analyze the coseismic slip model by Elliott et al (2013) and afterslip models (at 4 and 17 days) by Trasatti et al (2016Trasatti et al ( , 2023.…”

“…The codes and data used in this study are provided through the repository: Churchill (2023). Several of the slip models used are also available online through: Jiang et al (2021b), Floyd et al (2016, Yue et al (2021), http:// seismo.berkeley.edu/∼burgmann/RESEARCH/TURKEY/turkey.html Trasatti et al (2023), and the SRCMOD database (Mai & Thingbaijam, 2014). Additionally, Chris Rollins (El Mayor Cucapah) and Daniele Cheloni and Nicola D'Agostino (L'Aquila) allowed us to put their afterslip models (which were not stored online) in our repository.…”

Evidence for Tear Faulting from New Constraints of the 23 October 2011 Mw 7.1 Van, Turkey, Earthquake Based on InSAR, GPS, Coastal Uplift, and Field Observations

“…Several studies based on Interferometric Synthetic Aperture Radar (InSAR) observations of the Van earthquake have already been published (Elliott et al, 2013;Fielding et al, 2013;Feng et al, 2014;Moro et al, 2014;Trasatti et al 2016). All these studies are however limited to coseismic Synthetic Aperture Radar (SAR) datasets only from the descending orbit and far field Global Positioning System (GPS) data, which makes it difficult to constrain both the geometry of the fault rupture(s) and the rake angle accurately, and hence the distribution of reverse and strike slip components on the fault surface.…”