Abstract
Based on tide-gauge records, the Boso-Oki tsunami of Sept. 19, 1984 is investigated. Adding the present data, the magnitudes of the tsunamis generated near the trench triple junction off Boso Peninsula since 1927 are discussed in relation to earthquake magnitude (M, JMA scale and Ms). Judging from the diagram of attenuation of tsunami height with distance, the magnitude (Imamura-Iida scale) of the 1984 tsunami was determined to be m=0. This grade is very large for an earthquake with M=6.6 and Ms=6.7. The estimated source area agrees with the aftershock area, and the source length is 35km which is the normal size for the earthquake magnitude.According to the statistical relation, the magnitude values of the Boso-Oki tsunamis are one to two grade larger than the average tsunami magnitude. Such tsunami energy is five to ten times larger. Its characteristic behavior seems to be caused by the low-frequency earthquake and the high-angle (dip angle 34°-74°) dip-slip fault. For future tsunamis generated off Boso Peninsula, there is a need of careful precautions.
Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
