Slip distribution of the 2020 Elazig Earthquake (M-w 6.75) and its influence on earthquake hazard in the Eastern Anatolia


DOĞRU A., BULUT F., Yaltırak C. , AKTUĞ B.

GEOPHYSICAL JOURNAL INTERNATIONAL, vol.224, no.1, pp.389-400, 2021 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 224 Issue: 1
  • Publication Date: 2021
  • Doi Number: 10.1093/gji/ggaa471
  • Title of Journal : GEOPHYSICAL JOURNAL INTERNATIONAL
  • Page Numbers: pp.389-400

Abstract

We analysed coseismic surface displacements of the 2020 January 24 Elazig (M 6.75) Earth-quake using GPS (Global Positioning System) measurements to investigate the associated fault slip distribution and static stress change. Our geodetic analysis of 13 GPS sites surrounding the epicentre included data from four additional sites. We accurately located the nucleation point of the main shock at 38.310 degrees N, 39.081 degrees E (+/- 1.4 km) and at a depth of 5.2 +/- 1.2 km. Both seismograph and GPS-derived fault plane solutions confirmed that it has a nearly pure sinistral mechanism with a negligible obliquity. The main shock generated 29.2 cm average sinistral slip along an approximately 70 km long and 20 km wide section of the East Anatolian Fault. Based on its rupture size and average slip, its magnitude was found to be M-w 6.75. An average of 6.6 bars of stress drop occurred on the rupture plane. The rupture occurred bilaterally failing two separate segments both to the northeast and to the southwest of the nucleation point. Average sinistral slips were 14.6 and 47.4 cm along the southwestern and northeastern segments, respectively. Sinistral slip reached up to 53.1 cm along the southwestern segment and 110.5 cm along the northeastern segment. During the generation process of the 2020 earthquake, 78 per cent of the slip deficit had been released aseismically since 1875. Increasing Coulomb stress by an average of 2.5 bars, it substantially increased earthquake hazard on the 1874 (M7.1) rupture zone, which might have already accumulated 1.51 m slip deficit on its fully locked patches. Furthermore, increasing Coulomb stress by an average of 0.5 bars, it raised earthquake hazard on the 1893 (M 7.1) rupture zone, which might have already stored 1.01 m slip deficit along the fully locked patches.