Large Gas Reservoir Along the Rift Axis of a Continental Back-Arc Basin Revealed by Automated Seismic Velocity Analysis in the Okinawa Trough

Kota Mukumoto, Takeshi Tsuji, Andri Hendriyana

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Abstract

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.

Original languageEnglish
JournalGeophysical Research Letters
DOIs
Publication statusAccepted/In press - Jan 1 2019

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seismic velocity
troughs
rifting
trough
arcs
hydrothermal fluid
heat flow
gases
basin
heat transmission
hydrothermal circulation
low velocity zone
velocity structure
seismic reflection
P-wave
wave velocity
trapping
fluids
spatial resolution
profiles

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Earth and Planetary Sciences(all)

Cite this

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title = "Large Gas Reservoir Along the Rift Axis of a Continental Back-Arc Basin Revealed by Automated Seismic Velocity Analysis in the Okinawa Trough",
abstract = "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.",
author = "Kota Mukumoto and Takeshi Tsuji and Andri Hendriyana",
year = "2019",
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doi = "10.1029/2019GL083065",
language = "English",
journal = "Geophysical Research Letters",
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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

PY - 2019/1/1

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