[S-SS10] Strong Ground Motion and Earthquake Disaster

[SSS10-04] Establishing Correlations between Seismic Intensity, Microtremor Measurement, and Structural Damage to develop a Novel Intensity Formula for Maras Earthquake

*Nurcan Meral Ozel¹, Shinichiro Mori², Hitomi Murakami³, Maki Koyama⁴, Gulten Polat⁵, Dilek Kepekci¹, Yasemin Korkusuz Ozturk¹, Saki Yotsui⁶, Hiroyuki Goto⁷, Shigeto Osato⁸, Tatsuro Chiba⁹, Koji Hada¹⁰, Masayuki Yamada¹⁰, Takumi Hayashida¹¹, Mayumi Sakamoto¹² (1.Kandilli Observatory and Earthquake Research Institute, 2.Graduate School of Science and Engineering, Ehime University, Matsuyama, 3.Graduate School of Science and Technology for Innovation, Yamaguchi University, Ube, Japan, 4.River Basin Research Center, Gifu University, Gifu, Japan, 5.Yeditepe University, Istanbul, Turkiye, 6.The University of Tokyo, Tokyo, Japan, 7.Disaster Prevention Research Institute, Kyoto University, Kyoto, Japan, 8.Soil Research, Tokyo, Japan, 9.Advanced Technology Research Institute, Chiba Laboratory, Asia Air Survey, Tokyo, Japan, 10.NEWJEC, Osaka, Japan, 11.Building Research Institute, Tsukuba, Japan, 12.Graduate School of Disaster Resilience and Governance, University of Hyogo, Kobe, Japan)

The research conducted on the Kahramanmaraş earthquake of February 6, 2023, aimed to comprehensively understand the distribution of seismic intensity in the affected areas and develop a novel formula for calculating intensity specific to Eastern-Southeastern Turkey. This earthquake, the most devastating in Turkey's recent history, originated from the Narlι splay fault and spread bilaterally along the East Anatolian Fault (EAF), covering a significant seismic gap of the EAF and the Amanos Fault. It affected 11 provinces in Turkey's Southeast region and neighboring areas of Syria, resulting in a rupture length exceeding 300 km and causing over 50,000 fatalities.
The research analyzed seismic intensity across seven cities: Hatay, Gaziantep, Kahramanmaraş, Adιyaman, Malatya, Osmaniye, and Şanlιurfa. An online questionnaire survey was distributed to educational institutions in these provinces, gathering responses from 14,739 participants. Geocoordinate data were accurately collected using the ArcGIS survey123 system, contributing to initial survey findings that included damage observations.
Microtremor observations were conducted in Hatay, Gaziantep, Kahramanmaraş, and Adιyaman using the Kinkei seismic measuring device developed in Japan. Single-point microtremor measurements were taken at 20 locations within the earthquake zone, fault-fracture zones, and damaged residential areas, especially near AFAD seismic stations. Additionally, array microtremor measurements were conducted at 31 AFAD station locations with strong motion records. Examination of 39 microtremor measurements revealed a correlation between heavily damaged buildings and areas with Vs30 values below 180 m/s, indicating that regions with lower Vs30 values might be more prone to earthquake damage.
These observations, combined with the results of online intensity questionnaires and local soil amplifications, were used to investigate the relationship between microtremor amplification and seismic damage. The aim is to create a new intensity calculation formula tailored to the Eastern-Southeastern region of Turkey. The findings of this research are expected to significantly advance earthquake intensity assessment methods, particularly in areas with unique geological and seismic characteristics. The collaboration between Turkish and Japanese experts brings an international perspective to the study, potentially enhancing seismic risk assessment, preparedness strategies, and recovery efforts on a broader scale in the future.