Original Paper(Vol.63 No.3 pp.250-257)

Seismic-Derived Quality Factor for Lithology Classification around the Median Tectonic Line

Yasuto SHIGEI, Takeshi TSUJI, Toshifumi MATSUOKA, Michiharu IKEDA ,
Naoki NISHIZAKA and Yoshihiko ISHIKAWA

Abstract:We calculated quality factor from seismic reflection data in order to classify the lithology around the Median Tectonic Line (MTL). Since seismic velocity around the MTL was not accurately estimated, it was difficult to classify the lithology and characterize the MTL. To calculate quality factor from seismic data, we used two methods: (1) spectral ratio method and (2) peak frequency method. In this study, we applied these two methods for the multi-channel seismic reflection data as well as zero-offset Vertical Seismic Profiling (VSP) data acquired at MTL in Ehime Prefecture, Japan. The result shows that quality factor is significantly changed at the lithological boundary beneath the MTL. From the estimated quality factor, we interpret that lithological boundary beneath the MTL is dipping to north. This study further shows that quality factor can be useful seismic attribute for lithology classification, even when seismic velocity cannot be estimated.

Key Words:Quality factor, Spectral Ratio Method, Peak Frequency Method, Seismic reflection data, VSP data, Median Tectonic Line