[H-DS11] Tsunami and tsunami forecast

[HDS11-P02] Conceptual overview for the tsunami generation in the Marmara Sea, Turkiye and 1 January 2024 Noto Peninsula, Japan earthquake: similarities, differences, challenges

*CEREN OZER SOZDINLER¹, Taro Arikawa², Ahmet Cevdet Yalciner³, Toshitaka Baba⁴, AHMET ANIL DINDAR¹, BULENT AKBAS¹, Selcuk Toprak¹, Yoshiyuki Kaneda⁵ (1.Gebze Technical University Department of Civil Engineering, 2.Chuo University Department of Civil and Environmental Engineering, 3.Middle East Technical University Department of Civil Engineering, 4.Tokushima University Earthquake Engineering Laboratory, 5.Kagawa University Institute of Education, Research and Regional Cooperation for Crisis Management Shikoku)

Keywords:Submarine Landslide tsunamis, Tsunami numerical modeling, Marmara Sea-Turkiye, Noto Peninsula Earthquake

Turkiye lies at the crossroads of tectonic plates that forms active fault zones, such as North Anatolian Fault (NAF) and East Anatolian Fault (EAF) zones, with the potential of massive M>7.0 earthquakes. Marmara Region is located at the northwestern part of Turkiye in which the northern strand of NAF extends from eastern Turkiye towards the Marmara Sea as a major strike slip fault. There are plenty of other fault segments in the Marmara Sea that had caused significant earthquakes with huge damage and loss of lives during the history. Besides, the coasts of Marmara Sea had been hit by destructive tsunamis in the past that could be proved by paleotsunami studies, historical records and the tsunami numerical modeling results. Tsunami generation occurs in the Marmara Sea not only by the fault rupture but also due to the triggering of submarine landslides. Many geological and related studies prove that there are several submarine landslide locations in the Marmara Sea, which have a high potential of generating significant tsunamis with short arrival times having mainly near-field effect. As being the center of Turkish economy with the great number of industrial facilities in largest capacity and potential, refineries, ports and touristic attractions, tsunami hazard assessment and strategies for the development of disaster-resilient communities become crucial in the Marmara Region. The short arrival time of tsunamis and difficulties in the estimation of tsunami generation due to submarine landslides makes issuing tsunami warning messages quite challenging. On the 1st of January 2024, a massive earthquake of magnitude 7.6 occurred on the Noto Peninsula, Japan that caused many deaths, injuries, collapse of houses and buildings, fires, and landslides. Japan Meteorological Agency issued a major tsunami warning first for Noto, Ishikawa Prefecture and then for the neighborhoods short after the earthquake. Tsunamis up to 1.2m were observed at Noto Peninsula coasts that were less than the expected values due to the huge crustal uplift especially at the coasts of Wajima city. The tsunami generation mechanism after Noto Peninsula earthquake should be examined in terms of rupture, triggering of submarine landslide(s) or both in order to better understand the challenges in alerting, evacuation and preparation. Japan and Turkiye has been conducting SATREPS project titled “MARTEST – Establishment of a Research and Education Complex for Developing Disaster-Resilient Societies” with the cooperation of JST and JICA starting officially from 21 June 2023 for 5 years exactly aiming to contribute to the development of disaster-resilient communities in the Marmara Region. For this purpose, a comprehensive tsunami scenario database has been prepared in the Marmara Sea including both earthquake and submarine landslide sources with deterministic and probabilistic approach. An extensive decision support platform will be developed for disaster risk reduction, mainly including earthquake and tsunami hazard assessment and damage assessment as well as urban planning at the coastal areas of Marmara Sea. The experience in Noto Peninsula earthquake and tsunami is contributing to the research activities held in MARTEST project in terms of evaluation of tsunami sources and effect of crustal uplift at the coast prior to the tsunami inundation. This study discusses the similarities, differences and challenges of tsunami generation in Marmara Sea, Turkiye and Noto Peninsula, Japan in terms of source mechanisms, short arrival times, near-field effects and vulnerabilities.