Journal of Physics of the Earth
Online ISSN : 1884-2305
Print ISSN : 0022-3743
ISSN-L : 0022-3743
Q and Site Amplification Factors of Hard-Rock Region in the Kitakami Massif, Northeastern Japan
Akiko HasemiToru MatsuzawaAkira HasegawaNorihito UminoToshio KonoSyuichiro HoriAkihiko ItoSadaomi SuzukiHaruyoshi Ishikawa
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1997 Volume 45 Issue 6 Pages 417-431


We observed three explosions along a 60 km profile in the central part of the Kitakami massif, northeastern Honshu, Japan. Explosion sites and most of the observation sites were located on hard-rock outcrops. Using P-wave first arrivals, the average QP along ray paths and site amplification factors were determined for the frequency range between 6 and 30 Hz based on the amplitude spectra decay with distance. QP increased proportional to fn (n_??_0.9). The difference in amplification factors among hard-rock sites was as much as a factor of five for frequencies lower than 12 Hz and became large at higher frequencies. QS and S-wave site amplification factors were obtained only for 5 and 7.5 Hz. QS was slightly larger than QP, but the difference was not significant. S-wave site amplification factors were more variable than those of P-wave among the stations.

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