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Coseismic slip model for 2020 Ghotor earthquake based on InSAR DATA
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Mahin Jafari *   , Zahra Mousavi , Abdolreza Ghods |
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Abstract: (628 Views) |
The Ghotor doublet earthquake happened on 23 Feb 2020 near Khoy and Salmas cities in west Azerbaijan province of Iran near Iran-Turkey border .The first large event with a magnitude of 5.8 Mww (USGS) happened at 5:52 UTC (9:23 AM local time) and followed by a second large event of magnitude 6.0 Mw (USGS) at 16:00 UTC. The second event inflicted most of the building damages. No surface rupture has been reported for the events. We estimated the areal extent of the surface displacement related to the 2020 Ghotor doublet earthquakes using three sets of C-band imagery from the European Space Agency Sentinel 1A and 1B satellites. Due to small ground displacement, we could not model the fault geometry of the first mainshock. The ascending and descending displacement maps of the second main shock are used to jointly invert the causative fault plane parameters. To obtain the source parameters, we first down-sampled the unwrapped LOS surface displacements by a quadtree algorithm and then inverted the unwrapped interferograms to infer the geometry of a single rectangular plane with uniform slip in a uniform elastic half-space. The fault geometry parameters are location (X, Y, and Depth), size (length and width), orientation (strike, dip, and rake), and uniform slip of the rupture plane. We assume the X, Y, and depth to correspond to the center of the top edge of the rupture plane. We used a nonlinear inversion method as implemented in the open-source software called Geodetic Bayesian Inversion Software (GBIS) released by Centre for Observation and Modeling of Earthquakes, Volcanoes, and Tectonics (COMET). We used Okada‘s (1985) displacement green functions to model the displacement field. The calculated optimal model illustrates a northeast-striking (N24°) left-lateral rupture plane dipping ~86° towards the west. Once the geometry of the fault plane with uniform slip was estimated, we expanded the rupture plane 20 km along-strike and 12 km along down-dip directions and divided it into 1291 individual patches to obtain the distributed slip on the rupture plane. Each patch has a fixed geometry according to optimal source parameters obtained from the nonlinear modeling, and the slip was allowed to vary freely on the fault plane. We used a modified version of the open-source software called FaultResampler 1.4 to apply the linear inversion for calculating slip distribution on the rupture plane. The coseismic rupture concentrates around a center depth of 3 km with a maximum slip of 97±8 cm. Assuming a rigidity modulus of 30 GPa, the geodetic moment is estimated to be 1.517E+18 Nm, equivalent to a moment magnitude of 6.05 Mw.
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Article number: 4 |
| Keywords: Ghotor earthquake, fault parameter, InSAR, slip distribution, Okada |
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Full-Text [PDF 1148 kb]
(239 Downloads)
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Type of Study: Research |
Subject:
Geo&Hydro
Received: 2023/03/26
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| References |
1. Bagnardi, Marco, and Andrew Hooper. "Inversion of surface deformation data for rapid estimates of source parameters and uncertainties: A Bayesian approach." Geochemistry, Geophysics, Geosystems 19, no. 7 (2018): 2194-2211. [ DOI:10.1029/2018GC007585] 2. Barnhart, W. D., and R. B. Lohman. "Automated fault model discretization for inversions for coseismic slip distributions." Journal of Geophysical Research: Solid Earth 115, no. B10 (2010). [ DOI:10.1029/2010JB007545] 3. Doin, Marie-Pierre, S. Guillaso, R. Jolivet, C. Lasserre, F. Lodge, Gabriel Ducret, and Raphael Grandin. "Presentation of the small baseline NSBAS processing chain on a case example: The Etna deformation monitoring from 2003 to 2010 using Envisat data." In Proceedings of the Fringe symposium, pp. 3434-3437. Frascati, Italy: ESA SP‐697, 2011. 4. Ghods, Abdolreza, Esmaeil Shabanian, Eric Bergman, Mohammad Faridi, Stefanie Donner, Gholamreza Mortezanejad, and Asiyeh Aziz-Zanjani. "The Varzaghan-Ahar, Iran, Earthquake Doublet (M w 6.4, 6.2): implications for the geodynamics of northwest Iran." Geophysical Journal International 203, no. 1 (2015): 522-540. [ DOI:10.1093/gji/ggv306] 5. Jackson, James, and Dan McKenzie. "Active tectonics of the Alpine-Himalayan Belt between western Turkey and Pakistan." Geophysical Journal International 77, no. 1 (1984): 185-264. [ DOI:10.1111/j.1365-246X.1984.tb01931.x] 6. Jónsson, Sigurjón, Howard Zebker, Paul Segall, and Falk Amelung. "Fault slip distribution of the 1999 M w 7.1 Hector Mine, California, earthquake, estimated from satellite radar and GPS measurements." Bulletin of the Seismological Society of America 92, no. 4 (2002): 1377-1389. [ DOI:10.1785/0120000922] 7. Okada, Yoshimitsu. "Surface deformation due to shear and tensile faults in a half-space." Bulletin of the seismological society of America 75, no. 4 (1985): 1135-1154. [ DOI:10.1785/BSSA0750041135] 8. Taymaz, Tuncay, Haluk Eyidog̃an, and James Jackson. "Source parameters of large earthquakes in the East Anatolian Fault Zone (Turkey)." Geophysical Journal International 106, no. 3 (1991): 537-550. [ DOI:10.1111/j.1365-246X.1991.tb06328.x] 9. Taymaz, Tuncay, Athanassios Ganas, Manuel Berberian, Tuna Eken, T. Serkan Irmak, Vasilis Kapetanidis, Seda Yolsal-Çevikbilen et al. "The 23 February 2020 Qotur-Ravian earthquake doublet at the Iranian-Turkish border: Seismological and InSAR evidence for escape tectonics." Tectonophysics 838 (2022): 229482. [ DOI:10.1016/j.tecto.2022.229482] 10. Wessel, Paul, and Walter HF Smith. "New version of the generic mapping tools." Eos, Transactions American Geophysical :union: 76, no. 33 (1995): 329-329. [ DOI:10.1029/95EO00198] 11. Hanssen, Ramon F. "Radar interferometry: data interpretation and error analysis." Vol. 2. Springer Science & Business Media, (2001). [ DOI:10.1007/0-306-47633-9] 12. Massonnet, Didier, and Kurt L. Feigl. "Radar interferometry and its application to changes in the Earth's surface." Reviews of geophysics 36, no. 4 (1998): 441-500. [ DOI:10.1029/97RG03139] 13. Funning, Gareth J., Barry Parsons, Tim J. Wright, James A. Jackson, and Eric J. Fielding. "Surface displacements and source parameters of the 2003 Bam (Iran) earthquake from Envisat advanced synthetic aperture radar imagery." Journal of Geophysical Research: Solid Earth 110, no. B9 (2005). [ DOI:10.1029/2004JB003338] 14. Vajedian, Sanaz, Mahdi Motagh, Zahra Mousavi, Khalil Motaghi, Eric J. Fielding, Bahman Akbari, Hans-Ulrich Wetzel, and Aliakbar Darabi. "Coseismic deformation field of the Mw 7.3 12 November 2017 Sarpol-e Zahab (Iran) earthquake: A decoupling horizon in the northern Zagros Mountains inferred from InSAR observations." Remote Sensing 10, no. 10 (2018): 1589. [ DOI:10.3390/rs10101589] |
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