木下 正高 教授らの論文が、日本地質学会 Island Arc賞を受賞しました。受賞論文：Ayumu Miyakawa, Saneatsu Saito, Yasuhiro Yamada, Hitoshi Tomaru, Masataka Kinoshita and Takeshi Tsuji, 2014, Gas hydrate saturation at Site C0002, IODP Expeditions 314 and 315, in the Kumano Basin, Nankai trough. Island Arc, 23, 142–156.
Miyakawa et al. (2014) estimated the degree of gas hydrate saturation at IODP Site C0002 in the Kumano Basin, Nankai Trough from logging-while-drilling logs and core samples obtained during IODP Expeditions 314 and 315 using Deep Sea Drilling Vessel Chikyu. Based on the excellent geophysical and geochemical data, the free gas migration in sediment is well illustrated. They found coexistence of gas hydrate and free gas, suggesting a large gas flux flowing to the southern and seaward edge of the basin from a deeper part of the Kumano Basin. This knowledge is applicable to various kinds of pore fluids and thus important to consider digenetic process of sedimentary rocks. This paper presents one of important results of gas hydrate formation obtained by the NanTroSEIZE drilling program using Chikyu. Their work has been broadly cited as the standard of the gas hydrate saturation in the seaward edge of the Kumano Basin, Japan. In addition, their findings motivate further studies on the coexistence of gas hydrate and free gas and the fluid migration in the area.
Ayumu Miyakawa graduated from Kyoto University with a BSc in 2006; he subsequently completed a Ph.D. course at the same university with the degree in 2011. He became a Postdoctoral Researcher at Japan Agency for Marine-Earth Science and Technology (JAMSTEC) in 2011; he served there for one year. In April 2012, he started his engagement in research at the Geological Survey of Japan (GSJ) in the National Institute of Advanced Industrial Science and Technology (AIST); he is a Senior Researcher since October 2017. His main interest is in the dynamics of subduction zones. He joined Nankai Trough Seismogenic Zone Experiment as an onboard logging scientist in IODP Expedition 314. The logging data obtained during the cruse revealed the fluid migration and the hydrate deposition within the forearc basin, as mentioned in the awarded article. He is also curious about the integration of the geological/geophysical observation such as the logging data and the geodynamics modeling. He is conducting the numerical modeling to simulate the dynamics of the subduction zones. Currently, he is expanding his research to crustal stress controlling the reactivation of the fault and the openness of the fault-fracture conduit in the crust.