Japan Geoscience Union Meeting 2018

Presentation information

[EE] Evening Poster

S (Solid Earth Sciences) » S-IT Science of the Earth's Interior & Tectonophysics

[S-IT24] Probing the Earth's interior with geophysical observation on seafloor

Tue. May 22, 2018 5:15 PM - 6:30 PM Poster Hall (International Exhibition Hall7, Makuhari Messe)

convener:Daisuke Suetsugu(Department of Deep Earth Structure and Dynamics Research, Japan Agency for Marine-Earth Science and Technology), Guilhem BARRUOL(CNRS, Institut de Physique du Globe de Paris, France), Hitoshi Kawakatsu(東京大学地震研究所, 共同), Douglas Wiens(Washington University in St Louis)

[SIT24-P01] The OJP array: seismological and electromagnetic observation on seafloor and islands in the Ontong Java Plateau

*Daisuke Suetsugu1, Hajime Shiobara2, Hiroko Sugioka4, Noriko Tada1, Aki Ito1, Takehi Isse2, Kiyoshi Baba2, Hiroshi Ichihara3, Toyonobu Ota5, Yasushi Ishihara1, Satoru Tanaka1, Masayuki Obayashi1, Takashi Tonegawa1, Junko Yoshimitsu1, Takumi Kobayashi4, Hisashi Utada2 (1.Department of Deep Earth Structure and Dynamics Research, Japan Agency for Marine-Earth Science and Technology, 2.Earthquake Research Institute, the University of Tokyo, 3.Earthquake and Volcano Research Center Graduate School of Environmental Studies, Nagoya University, 4.Graduate School of Science, Kobe University, 5.Tierra Tecnica, Ltd.)

Keywords: Ontong Java Plateau, Large Igneous Provinces, BBOBS, OBEM

We conducted geophysical observations on the Ontong Java Plateau (OJP) and its vicinity from late 2014 to early 2017 to determine the underlying crust and upper mantle structure beneath the OJP. The OJP was emplaced in the present South Pacific region at 120 and 90 Ma by massive volcanism, but the causes of this volcanism are still debated. Previous studies have suggested that seismic velocity beneath the OJP is anomalously slow, thus could represent thermal or chemical remnants of the volcanism. However, the seismic resolution of the slow anomalies is poor due to lack of seafloor observations. The observation network named “the OJP array” is composed of seafloor and island stations. The seafloor stations have broadband ocean bottom seismographs and ocean bottom electromagnetometers. The island stations have broadband seismographs. The OJP array is designed to obtain seismic and electrical conductivity structures of the mantle beneath the OJP with better resolution than that of previous studies. Joint analysis and interpretation of seismological and electromagnetic data should provide tight constraints to thermal and chemical structures and clarify the cause of OJP emplacement.