Japan Geoscience Union Meeting 2024

Presentation information

Print

[J] Oral

S (Solid Earth Sciences ) » S-CG Complex & General

[S-CG54] Volcanoes in the sea

Fri. May 31, 2024 1:45 PM - 3:00 PM 301B (International Conference Hall, Makuhari Messe)

convener:Yoshihiko Tamura(Research Institute for Marine Geodynamics, Japan Agency for Maine-Earth Science and Technology), Eisuke Fujita(National research Instituite for Earth science and Disaster Resilience, Volcanic research department), Fukashi Maeno(Earthquake Research Institute, University of Tokyo), Shigeaki Ono(Japan Agency for Marine-Earth Science and Technology), Chairperson:Yoshihiko Tamura(Research Institute for Marine Geodynamics, Japan Agency for Maine-Earth Science and Technology), Shigeaki Ono(Japan Agency for Marine-Earth Science and Technology), Fukashi Maeno(Earthquake Research Institute, University of Tokyo), Eisuke Fujita(National research Instituite for Earth science and Disaster Resilience, Volcanic research department)

2:45 PM - 3:00 PM

[SCG54-15] Analysis of T-phases associated with the 2022 Tonga volcanic eruptions recorded by MERMAIDs

*Satoshi Murakami 1, Masayuki Obayashi2, Hiroko Sugioka1, Joel D Simon3, Yong Yu4, Junko Yoshimitsu2, Yuko Kondo1 (1.Kobe University, 2.Japan Agency for Marine-Earth Science and Technology, 3.Princeton University, 4.Southern University of Science and Technology)

Keywords:Hunga Tonga, MERMAID, T-phase

On January 15, 2022 at 04:14:45 UTC, a enormous eruption occurred at Hunga Tonga-Hungaa Ha'apai. Several eruptions are known to have occurred before and after this eruption between 04:00 and 04:30 UTC (Tarumi,et.al 2023), and various secondary phenomena (atmospheric waves, and meteo tsunamis, seismic recorded worldwide) from these eruptions have been observed(Matoza et,al 2022), and T-wave generated by this series of eruptions have been observed by several MERMAIDs and the hydrophone triplets H03N and H03S of the International Monitoring System (IMS) off Chile.The MERMAID is an autonomous float equiped with a hydrophone to observe underwater sound waves converted from high-frequency (~1 Hz) P waves at the seafloor and transmits the waveform data in quasi-real time via satellite communication for the purpose of determining the Earth's deep interior structure and MERMAID has a system that automatically transmits seismic P-waves in quasi-real time, while also storing about one year of continuous data to extract data from a specified period of time by requesting it from shore, even during periods when the data is not automatically transmitted.We obtained data length of about an hour that observed T-wave associated with these eruptions on request from about 50 MERMAID units operating in the South Pacific.The feature of these eruptions of Hunga Tonga-Hunga Ha'apai captured by T-waves, was distinguished into three phases. Phase 2 has the largest amplitude, Phase 1 is that repeated a single event before Phase 2, Phase 3 has continuous high amplitude after Phase 2, but these features are different with those by seismometer. In this study, using the envelope waveforms of the MERMAID and IMS hydrophone data, we measured travel time differences between two stations for each phase by the correlation method and obtained the T-wave source for each phase from the travel time difference data.