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7-4. 2000 Tottoriken-Seibu earthquake

 The 2000 Tottoriken-Seibu earthquake (M7.3, temporally determined) occurred on October 6. Figure
1 shows an aftershock distribution from Oct. 6 to Jan. 16, 2000, located by the combined DPRI's
data(KYT) with Hi-net. The aftershock distribution was about 30 km long in the direction of NNE-SSW,
and shallower than 15 km. The mainshock hypocenter was determined at a depth of about 5 km. Yellow
circles indicate the temporal microseismic observation stations installed by the Japanese university
group of the urgent joint observation for the 2000 Tottoriken-seibu Earthquake in order to investigate
precise crustal structure and focal mechanisms and etc..

 The rupture process of the Tottoriken-Seibu earthquake is revealed using strong motion
seismograms installed around the source region. The spatial distribution of final slip is shown in Fig. 2.
The fault plane on the south side of the epicenter has 14 km long and 13 km wide with the strike of
N142°E, and that on the north side has 16 km long and 13 km wide with the strike of N158°E. The
large slip area lies around the hypocenter with the depth of 2 km to 6 km deep. The largest slip and the
seismic moment are 4m and 1.2 x 10 19 Nm, respectively.

 To observe the postseismic deformation we deployed newly developed one frequency GPS receivers
from October 11 to December 27, 2000. The linear GPS array was constructed around the epicenter
and it is perpendicular to the aftershock distribution. Figure 3 shows the average horizontal
displacement from October 11 to November 2, 2000. The postseismic deformation was observed.
 


Fig.1. Aftershock distribution of an earthquake of October 6, 2000 in the Western Part
    of Tottori Prefecture (Oct. 2000 - Jan. 2001). The aftershocks were located in
          shallower than 15 km by the combined DPRI's data(KYT) with Hi-net.

Fig.2. Rupture process of the Tottoriken-Seibu earthquake viewing from the west.

Fig.3. Average horizontal deformation vector between October 11 and November 2.



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