Name : YAMANO, Makoto
Position : Associate Professor
Division/Center : Ocean Hemisphere Research Center
Research Area : Geothermics, Tectonophysics
Name : YAMANO, Makoto
Position : Associate Professor
Division/Center : Ocean Hemisphere Research Center
Research Area : Geothermics, Tectonophysics
Research :
My main research interest is investigation of the thermal structure
of subduction zones through measurements of terrestrial heat flow
and numerical thermal models of
subduction taking account of other geophysical, geological and petrological
information. Since physical
properties of rocks strongly depend
on temperature, various processes in subduction zones such as seismic activity,
crustal
deformation, magmatism, and metamorphism
should be closely related to the thermal structure. We calculated the temperature
distribution along the plate interface
in several subduction zones and showed that the temperature is one of the
major factors which
determine the downdip limit of
the seismogenic zone of subduction thrust faults. In most subduction zones,
however, heat flow data in
the arc-trench gap is too sparse
to constrain the thermal structure model well. We have recently started
detailed heat flow
measurements in the Nankai subduction
zone, which is one of the main targets of international research projects
on seismogenic
zones (SEIZE and OD21), in order
to obtain better information on the temperature along the plate interface.
I am also interested in thermal
structure and evolution of back-arc basins. We recently made heat flow
measurements in the Derugin
Basin, Sea of Okhotsk and constructed
a thermal evolution model of the basin since its formation by rifting of
continental lithosphere. I
have been investigating the heat
flow versus age relationship for back-arc basins as well. Observation of
detailed heat flow
distributions may provide information
on fluid flow regimes in sediments and uppermost crust in active hydrothermal
areas and in cold
seepage areas at convergent margins.
We have been conducting closely-spaced heat flow measurements and long-term
temperature
monitoring in such areas to investigate
the spatial pattern of pore fluid flows and its temporal variation, e.g.
in the Okinawa Trough
and Sagami Bay.
I have been developing new seafloor
observation devices such as temperature monitoring systems for submersibles,
pop-up type
temperature probes, and a long-term
pore-pressure instrument. The main purposes are determination of heat flow
in shallow sea
areas with significant bottom
water temperature variations, heat flow measurements on seafloor with no
soft sediment cover, and
detection of temporal variations
in pore fluid flows. Some of them have already been deployed for up to
one year and produced useful
data.
Publications :
1.Kinoshita, M., and M. Yamano, Hydrothermal regime
and constraints on reservoir depth of the Jade site in the Mid-Okinawa
Trough
inferred from heat flow measurements,
J. Geophys. Res., 102, 3183-3194, 1997.
2.Hyndman, R. D., M. Yamano, and D. A. Oleskevich,
The seismogenic zone of subduction thrust faults, Island Arc, 6, 244-260
1997.
3.Kinoshita, M., S. Goto, and M. Yamano, Estimation
of thermal gradient and diffusivity by means of long-term measurements
of
subbottom temperatures at western
Sagami Bay, Japan, Earth Planet. Sci. Lett., 141, 249-258, 1996.
4.Hyndman, R. D., K. Wang, and M. Yamano, Thermal
constraints on the seismogenic portion of the southwestern Japan subduction
thrust, J. Geophys. Res., 100,
15,373-15,392, 1995.