[vc_empty_space][vc_empty_space]
Large Gas Reservoir Along the Rift Axis of a Continental Back-Arc Basin Revealed by Automated Seismic Velocity Analysis in the Okinawa Trough
Mukumoto K.a, Tsuji T.a, Hendriyana A.a,b
a Department of Earth Resources Engineering, Kyushu University, Fukuoka, Japan
b Exploration and Engineering Seismology Research Group, Bandung Institute of Technology, Bandung, Indonesia
[vc_row][vc_column][vc_row_inner][vc_column_inner][vc_separator css=”.vc_custom_1624529070653{padding-top: 30px !important;padding-bottom: 30px !important;}”][/vc_column_inner][/vc_row_inner][vc_row_inner layout=”boxed”][vc_column_inner width=”3/4″ css=”.vc_custom_1624695412187{border-right-width: 1px !important;border-right-color: #dddddd !important;border-right-style: solid !important;border-radius: 1px !important;}”][vc_empty_space][megatron_heading title=”Abstract” size=”size-sm” text_align=”text-left”][vc_column_text]©2019. American Geophysical Union. All Rights Reserved.In the Okinawa Trough off southwestern Japan, hydrothermal circulation due to back-arc rifting is active. Biogenic CH4 in discharging hydrothermal fluids at the Iheya North Knoll is derived from outside the knoll; however, the location of the gas reservoir has not been identified. Here, we applied automated velocity analysis to seismic reflection data to obtain a P wave velocity structure in high spatial resolution. The resulting profiles reveal large gas reservoirs as low-velocity zones along the rifting axis (>5 km for axis direction) around the Iheya North Knoll. The main gaseous components in the reservoir could be CO2 and CH4. The heat flow inferred from seismic profiles (i.e., depth of reflector) indicates that CH4 hydrate could be trapping the gas. Furthermore, the heat flow is higher at the rifting axis and close to the knoll, reflecting the large gas reservoir feeding the hydrothermal fluids in the discharging area at the knoll.[/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”Author keywords” size=”size-sm” text_align=”text-left”][vc_column_text]Back-arc basin,Gas reservoir,High spatial resolution,Hydrothermal circulation,Hydrothermal system,P-wave velocity structure,Seismic reflection method,Seismic velocity analysis[/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”Indexed keywords” size=”size-sm” text_align=”text-left”][vc_column_text]continental back-arc basin,gas reservoir,heat flow,hydrothermal system,seismic reflection method[/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”Funding details” size=”size-sm” text_align=”text-left”][vc_column_text]We thank two anonymous reviewers for a careful review and helpful suggestions. We thank the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) for providing seismic data and Yuka Masaki (Cosmos Shoji Co.) for providing seafloor temperature information. The original seismic data are available from JAMSTEC website (http://www.godac.jamstec.go.jp/darwin/data/kairei/kr10-02/pi129/e). The P wave velocity and migrated seismic profiles we estimated in this study (Figures, , S2, S3) can be downloaded from the following URL (http://geo.mine.kyushu-u.ac.jp/tsuji/vp_iheya/index.html). This work is partially supported by the agency’s Strategic Innovation Promotion Program. We are grateful for the support of the International Institute for Carbon Neutral Energy Research (I2CNER), which is sponsored by the World Premier International Research Center Initiative of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japan. All authors analyzed the data, interpreted the results, and described the manuscript. T. T. convinced this study. K. M. mainly performed data analysis. T. T. and A. H. mainly supervised seismic data processing and interpretation.[/vc_column_text][vc_empty_space][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][vc_empty_space][megatron_heading title=”DOI” size=”size-sm” text_align=”text-left”][vc_column_text]https://doi.org/10.1029/2019GL083065[/vc_column_text][/vc_column_inner][vc_column_inner width=”1/4″][vc_column_text]Widget Plumx[/vc_column_text][/vc_column_inner][/vc_row_inner][/vc_column][/vc_row][vc_row][vc_column][vc_separator css=”.vc_custom_1624528584150{padding-top: 25px !important;padding-bottom: 25px !important;}”][/vc_column][/vc_row]