Estimation of the 3-D velocity structure of the Sorachi–Yezo and Oshima Belts in the western part of Hokkaido, Japan
Kawahara, IIsmail Husain Fathi & Kaoru Miyashita & Jun . 2013
We adopted the seismic tomography technique to
refine the three-dimensional velocity structure model of the
western part of Hokkaido, Japan. Using the P-wave first
arrival data listed by Japan Meteorological Agency from
2002 to 2005, we could estimate a 3-D inhomogeneous velocity
structure model with a low velocity at a depth of 14 km
beneath Asahikawa. The crustal structure near Sapporo was
characterized by lateral velocity change toward the southern
seaside. The low-velocity zone near Urakawa, proposed by
previous research, was also clarified. In general, the present
model showed lower-velocity values for most of the crustal
layers in the area concerned. The results of this study were
affected by less number of higher magnitude events (M≥0.5)
in the central part of the area of interest. However, the perturbation
results for comparatively shallow layers (6–50 km)
were good in resolution. It was found that the source region
of the Rumoi–Nanbu earthquake of December 14, 2004 was
characterized by a low-velocity zone, located between high
velocity zones. Such an inhomogeneous crustal structure
might play an important role in the relatively high
seismic activity in the Rumoi–Nanbu earthquake source
region.
Applying the iterative shooting/bisection technique
for rapid forward modeling to the seismic explosion
data, we could refine the crustal velocity structure model of
the western…
We adopted the seismic tomography technique to
refine the three-dimensional velocity structure model of the
western part of Hokkaido, Japan. Using the P-wave first
arrival data…