04 May 2020

04 May 2020

Review status: this preprint was under review for the journal SE but the revision was not accepted.

Seismicity related to the eastern sector of Anatolian escape tectonic: the example of the 24 January 2020 Mw 6.77 Elazığ-Sivrice earthquake

Mohammadreza Jamalreyhani1,2, Pınar Büyükakpınar1,3, Simone Cesca1, Torsten Dahm1, Henriette Sudhaus1,4, Mehdi Rezapour2, Marius Paul Isken1,4, Behnam Maleki Asayesh5, and Sebastian Heimann1 Mohammadreza Jamalreyhani et al.
  • 1GFZ German research centre for geosciences, Potsdam, 14473, Germany
  • 2Institute of geophysics, University of Tehran, 14155-6466, Iran
  • 3Regional Earthquake Tsunami Monitoring Center, Kandilli Observatory and Earthquake Research Institute, Boğaziçi University, Istanbul, 34684, Turkey
  • 4Department of Geosciences, Christian-Albrechts-University Kiel, Kiel, 24118, Germany
  • 5International Institute of Earthquake Engineering and Seismology, Tehran, 19537-14453, Iran

Abstract. The 24 January 2020 Mw 6.77 Elazığ-Sivrice earthquake (Turkey), responsible for 42 casualties and ~ 1600 injured people, is the largest earthquake affecting the East Anatolian Fault (EAF) since 1971. The earthquake partially ruptured a seismic gap. The mainshock was preceded by two foreshocks with Mw ≥ 4.9 and small seismicity clusters occurring in the previous months close to the nucleation point of the main rupture. The significant aftershock sequence comprises twelve earthquakes with Mw ≥ 4.5 within 60 days. We jointly model quasi co-seismic static surface displacements from Interferometric Synthetic Aperture Radar (InSAR) and high-frequency co-seismic data from seismological networks at local, regional and teleseismic distances to retrieve source parameters of the mainshock. We reconstruct the rupture process using a Bayesian bootstrap based probabilistic joint inversion scheme to obtain source parameters and their uncertainties. Full moment tensor for 18 fore-/after-shocks with Mw ≥ 4.3 are obtained based on the modeling of regional broadband data. The posterior mean model for the 2020 Elazığ-Sivrice mainshock shows that the earthquake, with a magnitude Mw 6.77, ruptured at shallow depth (5 ± 2 km) with a left-lateral strike-slip focal mechanism, with a dip angle of 74° ± 2° and a causative fault plane strike of 242° ± 1°, which is compatible with the orientation of the EAF at the centroid location. The rupture nucleated in the vicinity of small foreshock clusters and slowly propagated towards WSW, with a rupture velocity of ~ 2100 ± 130 m s−1 and ~ 27 s rupture duration. The main rupture area, with a length of ~ 26 ± 5 km, only covered 70 % of the former seismic gap, leaving a smaller, unbroken segment of ~ 30 km length to the SE with positive stress change. The subsequent aftershock sequence extended over a broader region of ~ 70 km in length, spreading to both sides of the mainshock rupture patch into the regions experiencing a stress increase according to our Coulomb stress modeling. Our results support the hypothesis of a shallow locking depth of the Anatolian micro-plate, which has a possible implication to the seismic bursts along the EAF and alternating seismic activity on the North Anatolian and the East Anatolian faults.

Mohammadreza Jamalreyhani et al.

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Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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Mohammadreza Jamalreyhani et al.

Mohammadreza Jamalreyhani et al.


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Latest update: 08 Mar 2021
Short summary
We model the source of the 24 January 2020 Mw 6.77 Elazığ-Sivrice (Turkey) earthquake using a combination of different data and we analyzed its seismic sequences. This earthquake occurred in the east Anatolian fault and it has filled the large part of the former seismic gap zone. An unbroken part has left after this earthquake and has the potential to host a future earthquake. This work provides information about the fault system and helps to the mitigation of seismic hazard in Southern Turkey.