Extremely high heat flow anomaly in the middle part of the Nankai Trough

Shear strength of sediments approaching subduction in the Nankai Trough, Japan as constraints on forearc mechanics

“…Due to the presence of a fossil spreading center, heat flow seaward of the trench on the Muroto transect is high (up to $200 mW/m 2 ) compared to the Ashizuri and Kumano transects ($100-130 mW/m 2 ) [Yamano et al, 1992;Yamano et al, 2003;Kinoshita et al, 2008]. Seismic reflection data reveal complex structure in the near-trench region on the Kumano transect (Figure 1).…”

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“…A significant volume of site survey data has been collected in the drilling area over many years, including multiple generations of two-dimensional seismic reflection (e.g., Park et al, 2002), wide-angle refraction (Nakanishi et al, 2002), passive seismicity (e.g., Obara et al, 2004), heat flow (Yamano et al, 2003), side-scan sonar, swath bathymetry, and submersible and remotely operated vehicle (ROV) dive data (Ashi et al, 2002). In 2006, Japan and the United States conducted a joint, three-dimensional (3-D) seismic reflection survey over a ~11 km × 55 km area, acquired by PGS Geophysical, an industry service company (Fig.…”

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“…Seismic studies/site survey data A significant volume of site survey data has been collected in the drilling area over many years, including multiple generations of 2-D seismic reflection (e.g., Park et al, 2002), wide-angle refraction (Nakanishi et al, 2002), passive seismicity, heat flow (Yamano et al, 2003), side-scan sonar, swath bathymetry, and submersible and remotely operated vehicle (ROV) dive studies (Ashi et al, 2002). In 2006, Japan and the United States conducted a joint 3-D seismic reflection survey over an ~11 km × 55 km area, acquired by PGS Geophysical, an industry service company (Moore et al, 2009).…”