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IUGG XXIV General Assembly July 2-13, 2007 Perugia, Italy
(S) - IASPEI - International Association of Seismology and Physics of the Earth's
Interior
JSS005 Oral Presentation 1908
Scaling of paleoseismological parameters of 550 behavioral segments in
Japan
Dr. Toshikazu Yoshioka
Active Fault Research Center Geological Survey of Japan, AIST IASPEI
Yasuo Awata, Yuichiro Fusejima, Fujika Miyamoto
Active faults in Japan are segmented into about 550 behavioral segments based on geometry of fault
strand separated by discontinuities of larger than about 2 km and bends, timing of paleo-faulting and
slip-rate. 550 behavioral segments consist of about 290 reverse faults, 40 normal faults and 220 strikeslip
faults. The maximum value in length among all behavioral segments is 66 kilometers and the
average value in length is about 20 kilometers. We gather paleoseismological data to construct the
active fault database in Japan, and evaluate paleoseismological fault parameters of each behavioral
segment, such as the fault length, the dip and strike, the long-term slip rate, the displacement-perearthquake,
the recurrence interval, and the elapsed time after the last faulting. To evaluate these
parameters, we use observed field data (mid-range value if they have some uncertainty) after the data
source references. In case there is no field data on the behavioral segment, we adopted the values
calculated from other parameters. We examined the relationships between these paleoseismological
parameters of the behavioral segments of active faults in Japan. In 65 behavioral segments, the
displacement-per-earthquake (D; net slip, most frequency-occurring value) was estimated from field
data. There is a good correlation between the lengths of behavioral segments (L) and D. The values of
D of the reverse faults are slightly higher than the values of the strike-slip faults. The average ratio
between D (m) and L (km) is about 0.15 in the reverse faults except for the Ichinose and Iriyamase
segments, and 0.12 in the strike-slip faults. The relationship between D and the long-term slip rate (S)
is also obvious. Behavioral segments with higher S tend to have higher values of D in over 1.0 mm/yr in
S. However, the values of D are almost flat in less than 1.0 mm/yr in S.
Keywords: fault, segment, parameter