[H-DS06] 津波とその予測

[HDS06-04] THE 06 FEBRUARY 2023 EASTERN TURKIYE EARTHQUAKE, SOURCES OF WATER MOTIONS, AND TSUNAMI IN THE EASTERN MEDITERRANEAN

*Gozde Guney Dogan¹、Ahmet Cevdet Yalciner¹、Isikhan Guler¹、Bilge Karakutuk¹、Furkan Demir¹、Didem Cambaz²、Vassilios Skanavis³、Costas Synolakis^3,4 (1.Middle East Technical University, Department of Civil Engineering, Ocean Engineering Research Center, Turkiye (METU)、2.Bogazici University, Kandilli Observatory and Earthquake Research Center, Turkiye (BOUN)、3.Academy of Athens, Greece、4.University of Southern California, USA)

キーワード：tsunami, eastern mediterranean, strike-slip earthquakes, landslides

A strong earthquake (Mw=7.7) of strike-slip faulting with epicenter (37.1123N 37.1195E) at a shallow depth striking about NE-SW on the East Anatolian fault zone occurred on 06^th February 2023 (01:17 UTC) in Kahramanmaras (eastern Türkiye). As the Tsunami Service Provider, KOERI issued four tsunami messages with a tsunami warning 15 min (after the earthquake) with expected tsunami amplitudes of 0.2m–0.5m along the southern coast of Türkiye. Although the epicenter is ~90 km inland, the earthquake generated a tsunami measured at four tide gauge stations, (Iskenderun, Erdemli, Gazimagusa (Famagusta), and Girne (Kerinya) in the Eastern Mediterranean. The recorded water motions have been analyzed after detiding to distinguish the arrival time of the wave and its profile. The tide gauge record (Iskenderun) shows a ~14 cm elevation and ~10 cm depression tsunami amplitude with approximately a 10 min wave period. The arrival time of the maximum wave is around 33 min after the earthquake. The first wave arrivals are around 36 min at Gazimagusa(Famagusta) and 48 min at Erdemli and Girne (Kerinya) stations. For the assessment of the 06 February 2023 tsunami, numerical simulations were performed using the tsunami numerical model NAMI DANCE. The arrival times of the waves at the four tide gauges indicate two separate tsunami origins for the Iskenderun and Erdemli & Gazimagusa (Famagusta). As the bathymetry is quite shallow in the Gulf of Iskenderun (~50-80 m), the first withdrawal time of 25 min suggests an origin within the gulf area, which results in later arrivals than recorded at Erdemli, Girne (Kerinya), and Gazimagusa (Famagusta) stations. Therefore, an elliptical subsidence of 1 m at maximum with 12x8 km dimensions is assumed near or offshore of Yumurtalik and Karatas districts in the sea, as a possible location among different source alternatives of the measured tsunami in Iskenderun. For the records measured at Erdemli, Girne (Kerinya), and Gazimagusa (Famagusta), three alternative tsunami source areas between Samandag, Türkiye, and Latakia, Syria are considered according to the tsunami arrival times. Mass movements are also possible, but such hypotheses definitely need more data and further analysis. The 06 February 2023 tsunami needs to be well understood regarding the source areas and generation mechanisms. A field survey was performed on 11-13 February 2023 to identify tsunami traces, conduct eyewitness interviews and help better define the types and locations of the sources. The simulations were repeated using the survey findings and the numerical results were compared with the measurements. The results will be discussed.