EGU23-17617, updated on 10 Jan 2024
https://doi.org/10.5194/egusphere-egu23-17617
EGU General Assembly 2023
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Multiple effects contributed to the intensive shaking recorded in the 6 February 2023 Kahramanmaraş (Türkiye) earthquake sequence

Sigurjón Jónsson1, Theodoros Aspiotis1, Tariq Aquib1, Eduardo Cano1, David Castro-Cruz1, Armando Espindola-Carmona1, Bo Li1, Xing Li1, Jihong Liu1, Rémi Matrau1, Adriano Nobile1, Kadek Palgunadi1, Laura Parisi1, Matthieu Ribot1, Cahli Suhendi1, Yuxiang Tang1, Bora Yalcin1, Ulaş Avşar2, Yann Klinger3, and P. Martin Mai1
Sigurjón Jónsson et al.
  • 1Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia (sigurjon.jonsson@kaust.edu.sa)
  • 2Middle East Technical University (METU), Ankara, Türkiye
  • 3Université de Paris Cité, Institut de Physique de Globe, CNRS, Paris, France

The Kahramanmaraş earthquake sequence caused strong shaking and extensive damage in central-south Türkiye and northwestern Syria, making them the deadliest earthquakes in the region for multiple centuries. The rupture of the first mainshock (M7.8) initiated just south of the East Anatolian Fault (EAF) and then ruptured bilaterally hundreds of km of the EAF, causing major stress changes in the region and triggering the second mainshock (M7.6) about 9 hours later. We mapped the surface ruptures of the two mainshocks using pixel-offset tracking of Sentinel-1 radar images and find them to be ~300 km and 100-150 km long. The distribution of aftershocks indicates that the fault ruptures may have been even longer at depth, or about ~350 km and ~170 km, respectively. The pixel-tracking results and finite-fault modeling of the spatially variable fault slip show up to 7 and 8 m of surface fault offsets at the two faults, respectively, and that fault slip was shallow in both events, mostly above 15 km. In addition, our back-projection analysis suggests the first mainshock ruptured from the hypocenter to the northeast towards the EAF (first ~15 sec), then continued along it to the northeast (until ~55 sec), and also to the southwest towards the Hatay province, later at high rupture speeds (until ~80 sec). Furthermore, strong motion recordings show PGA values up to 2g and are particularly severe in Hatay, where multiple stations show over 0.5g PGA values. Both events are characterized by abrupt rupture cessation, generating strong stopping phases that likely contributed to the observed high shaking levels. Together the results show that directivity effects, high rupture speed, strong stopping phases, and local site effects all contributed to the intensive shaking and damage in the Hatay province.

How to cite: Jónsson, S., Aspiotis, T., Aquib, T., Cano, E., Castro-Cruz, D., Espindola-Carmona, A., Li, B., Li, X., Liu, J., Matrau, R., Nobile, A., Palgunadi, K., Parisi, L., Ribot, M., Suhendi, C., Tang, Y., Yalcin, B., Avşar, U., Klinger, Y., and Mai, P. M.: Multiple effects contributed to the intensive shaking recorded in the 6 February 2023 Kahramanmaraş (Türkiye) earthquake sequence, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17617, https://doi.org/10.5194/egusphere-egu23-17617, 2023.