February 2023 Kahramanmaras, Turkey Earthquakes: Microtremor Measurement, Extensive Field Survey On Seismic Intensity &#160;And Structural Damage Correlations To Develop The New Intensity Formula For The Region
Authors: Meral Ozel Nurcan , Mori Shinichiro , Murakami Hitomi , Koyama Maki , Kepekçi Dilek , Polat Gulten , Korkusuz Ozturk Yasemin , Yotsui Saki , Goto Hiroyuki , Osato Shigeto , Chiba Tatsuro , Hada Koji , Yamada Masayuki , Hayashida Takumi , Sakamoto Mayumi 
Published: March 2024

The research conducted on the 6th of February 2023 Mw7.8 Kahramanmara&#351; earthquake representsa comprehensive study aimed at understanding the distribution of seismic intensity in the affectedareas and developing a novel intensity calculation formula for Eastern-Southeastern Turkey. Thisseismic event, the most catastrophic in Turkey&amp;#39;s last century, was initiated on the Narli splay faultand propagated bilaterally along the East Anatolian Fault (EAF). The rupture extended over asignificant seismic gap of the EAF and the Amanos Fault, affecting 11 provinces in Turkey&amp;#39;s Southeastregion and bordering areas of Syria, resulting in a total rupture length exceeding 300 km and causingover 50,000 fatalities.The study evaluates seismic intensity distribution across seven cities: Hatay, Gaziantep,Kahramanmara&#351;, Ad&#305;yaman, Malatya, Osmaniye, and &#350;anl&#305;urfa. An online intensity questionnairesurvey was distributed to educational institutions in these provinces. In October 2023, a Turkish-Japanese reconnaissance team collaborated with the National Education Directorate of the sevenprovinces to disseminate the questionnaire format and URL link to all public high schools, middleschools, and elementary schools, garnering responses from 14,739 participants. Geocoordinateinputs were accurately assigned using the ArcGIS survey123 system, contributing to the preliminarysurvey results which included damage observations.Microtremor observations were conducted in Hatay, Gaziantep, Kahramanmara&#351;, and Ad&#305;yamanusing the Kinkei seismic measuring device developed in Japan. The research involved single-pointmicrotremor measurements at 20 locations within the earthquake zone, fault-fracture zones,damaged residential areas, particularly near the AFAD seismic stations. Additionally, arraymicrotremor measurements were made at 31 AFAD station locations with strong motion records.The analysis of 39 microtremor measurements revealed preliminary results indicating a correlationbetween heavily damaged buildings and areas where the Vs30 values are less than 180 m/s. Thefinding suggests that areas with lower Vs30 values may be more susceptible to damage duringearthquakes.These observations, combined with the result of the online intensity questionnaire surveys and localsoil amplifications, are utilized to assess the correlation between microtremor amplification andseismic damage. The objective is to formulate a new intensity calculation formula tailored to theEastern-Southeastern part of Turkey. This research&amp;#39;s findings are anticipated to offer significantcontributions to earthquake intensity assessment methodologies, particularly in regions with distinctgeological and seismic profiles. The collaboration between Turkish and Japanese experts adds aninternational dimension to the study, potentially leading to improved seismic risk assessment,preparedness strategies, and recovery measures on a broader scale in the future.