Japan Geoscience Union Meeting 2024

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[E] Oral

S (Solid Earth Sciences ) » S-EM Earth's Electromagnetism

[S-EM12] Electric, magnetic and electromagnetic survey technologies and scientific achievements

Sun. May 26, 2024 1:45 PM - 3:00 PM 304 (International Conference Hall, Makuhari Messe)

convener:Tada-nori Goto(Graduate School of Science, University of Hyogo), Yoshiya Usui(Earthquake Research Institute, the University of Tokyo), Yuguo Li(Ocean University of China), Wiebke Heise(GNS Science, PO Box 30368, Lower Hutt, New Zealand), Chairperson:Wiebke Heise(GNS Science, PO Box 30368, Lower Hutt, New Zealand), Koki Aizawa(Institute of Seismology and Volcanology, Faculty of Sciences, Kyushu University), Shogo Komori(National Institute of Advanced Industrial Science and Technology)

2:45 PM - 3:00 PM

[SEM12-15] Preliminary Results achieved with the Numerical Modeling of the Magnetotellurics data collected at epicentral area of the Kahramanmaraş Earthquakes – I

*Sabri Bulent Tank1, Yasuo Ogawa2, Ryokei Yoshimura3, Masaki Matsushima4, Selda Altuncu5, Tülay Kaya6, Serhun Zoroglu6 (1.Bogazici University, Kandilli Observatory and Earthquake Research Institute, Istanbul, Türkiye, 2.Tokyo Institute of Technology, Institute of Innovative Research, Tokyo, Japan, 3.Kyoto University, Disaster Prevention Research Institute, Uji, Kyoto, Japan, 4.Tokyo Institute of Technology, Dept. Of Earth and Planetary Sciences, Tokyo, Japan, 5.Bogazici University, Kandilli Observatory and E.R.I., RETMC, Istanbul, Türkiye, 6.Bogazici University, Kandilli Observatory and E.R.I., Dept. of Geodesy, Istanbul, Türkiye)

Keywords:Magnetotellurics, Electrical Conductivity, Faults, Fluids

On February 6, 2023, two major and devastating earthquakes (with magnitudes 7.8 and 7.6) occurred in the East Anatolian Fault Zone, south-southeast Türkiye. Nine hours apart the catastrophic events took place one after the other in two close but distinct segments of the fault system. They are named Kahramanmaraş earthquake doublets. Early seismological studies claimed that the first event triggered the second one via stress transfer. In this study, we attempted to elucidate the distribution of subsurface fluids around the 1st epicenter by using magnetotellurics, a natural source electromagnetic method that is sensitive to electrical conductivity variations of the sub-surface. The survey was planned and conducted in September 2023 around the epicenter. Thirty-five wideband magnetotellurics observations were made with four- (Ex, Ey, Hx, and Hy) and two-channel (Ex and Ey) MT systems. The preliminary two- and three-dimensional numerical models achieved from 15 four-channel MT data collected around the 1st epicenter suggested that there is a highly conductive anomaly underneath the hypocentral area that may be interpreted as a fluid-rich zone. This result agrees well with the hypothesis that is being tested and claims that the fluid contribution is a crucial component in the earthquake generation process.