TY - JOUR
T1 - Large Gas Reservoir Along the Rift Axis of a Continental Back-Arc Basin Revealed by Automated Seismic Velocity Analysis in the Okinawa Trough
AU - Mukumoto, Kota
AU - Tsuji, Takeshi
AU - Hendriyana, Andri
N1 - Funding Information:
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.
Publisher Copyright:
©2019. American Geophysical Union. All Rights Reserved.
PY - 2019/8/28
Y1 - 2019/8/28
N2 - 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.
AB - 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.
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U2 - 10.1029/2019GL083065
DO - 10.1029/2019GL083065
M3 - Article
AN - SCOPUS:85071605952
SN - 0094-8276
VL - 46
SP - 9583
EP - 9590
JO - Geophysical Research Letters
JF - Geophysical Research Letters
IS - 16
ER -