Kyoko Kobayashi

Measuring quality of life in Japanese children: Development of the Japanese version of PedsQL

Background:  Health‐related quality of life (HRQL) is perceived as an important health‐care outcome. There are several systems for measuring the HRQL in adults but there are few such systems for children in Japan. Pediatric Quality of Life Inventory (PedsQL) is valid and demonstrates excellent reliability in the USA, Europe, and Asian countries. The aim of the present study was therefore to develop the Japanese version of PedsQL.

Tectonic context of fluid venting at the toe of the eastern Nankai accretionary prism: Evidence for a shallow detachment fault

During the Kaiko-Nankai diving cruise the peak of the venting activity was located near the top of the very first anticline. The most prominent morphological feature between the mid-slope (3870 m) and the apex of the fold (3770 m) is a 20 m high cliff cutting through subhorizontal massive mudstones affected by numerous joints. The trend of this scarp is oblique to the fold axis and structurally controlled along two sharply defined NNE-SSE and E-W directions. Fresh talus and blocks found locally suggest active tectonics and recent erosion. Intense deformation is evident from strongly tilted strata restricted to the base of the cliff that we interpret as an upslope thrust. At the scale of Seabeam mapping, this thrust can be followed eastward for more than 5 km along the 3820 m isobath. Two seismic lines recorded during one of the pre-site surveys show deformation at shallow depth, including small-scale folding and thrusting affecting only the wedge-shaped top sequence. Deeper layers can be traced continuously below this sequence. We conclude that the boundary between the “piggy-back” basin and the frontal fold turbidites acts as a shallow detachment fault, and interpret the base of the cliff as the outcrop of the fault. Dense colonies ofCalyptogena clams and strongly nonlinear thermal gradients locate the major peak of fluid activity at the edge of the plateau above the main cliff. Scattered biological colonies as well as white bacterial mats and cemented chimneys were also found in a narrow belt along the base of the cliff. Fluid activity is thus closely related to the shallow detachment fault, fluid being expelled both at the outcrop of the fault and above it through the overlying strata, possibly using the very dense joint network.

Deep-tow survey in the KAIKO-Nankai cold seepage areas

Deep-sea biological communities associated with cold venting were located within the eastern portion of the Nankai Trough using a deep-towed TV system. Five continuous lines (approximately 200 km long) were observed. Bivalve communities were found both in the Tenryu Canyon outlet region and at the outcrop of the frontal thrusts of the accretionary wedge off Cape Omaezaki. The former is a site at which biological communities had been found during the KAIKO dives in 1985. However, the second site appears to be associated with larger scale venting and was chosen for the 1989 KAIKO-Nankai submersible cruise. Three small mud volcanoes with diameters of several hundred meters and heights of several tens of meters are found in the Seabeam topography map, but the present survey showed neither evidence of recent venting nor biological communities.

Time-variations of fluid expulsion velocities at the toe of the eastern Nankai accretionary complex

Abstract The temperatures in the bottom seawater and down to a depth of 60 cm in the sediment were measured over two active fluid seeps at the toe of the eastern Nankai accretionary complex for periods of 12 and 32 days successively. At the first station, the fluid advection velocity is low (less than 10 m/a) and the sediment temperature fluctuations closely reflect those of seawater. At the second location, the fluid advection velocity is greater, with a Darcy velocity of the order of 100 m/a, and sediment temperature fluctutations mainly reflect variations in the fluid velocity. The temperature data suggest amplitude fluctuations of the fluid velocity of the order of 15% over characteristic periods of about 14 days. They also suggest a 30% increase in the velocity over the one month period of the observation.

Sub-Moho seismic profile in the Mariana Basin — Ocean bottom seismograph long-range explosion experiment

Abstract Ocean bottom seismograph (OBS) long-range explosion experiments were carried out in the Mariana Basin in 1973 and 1976. Seven large shots (8.5–1.5 ton) as well as several tens of small shots were fired. The maximum range of observation was about 1900 km. As many as 25 OBS stations were deployed in an array of about 800 km. It is found that the sub-Moho P-wave velocity structure is of stratified nature, being composed of alternating high- and low-velocity layers. High-velocity layers with apparent velocities of 8.1, 8.2, 8.4, 8.6 and 8.7 km/s are identified. Low-velocity layers, sandwiched between the high-velocity layers of 8.4, 8.6 and 8.7 km/s, are very prominent. The sub-Moho high-velocity lid with an apparent velocity of 8.4 km/s is very thin. Thinning of this lid, thickening of the low-velocity layer, and the presence under it of another high-velocity layer (8.6 km/s) appear to characterize the uppermost mantle structure beneath the Mariana Basin.

Shear partitioning in the eastern Nankai Trough: evidence from submersible dives

Abstract Submersible dives over the wedge of the easternmost Nankai Trough demonstrate the existence of a left-lateral strike-slip system parallel to the subduction zone. This system develops as the trench, turning northward toward land, becomes highly oblique to the motion. Although shear partitioning is well known in other subduction zones, the process here has the peculiarity of continuing northward into land.