The shape of the coastlines along Kamaishi Bay, Ishinomaki Bay and four other areas in Tohoku may have amplified the power of the tsunami that struck there last March, a study by tsunami researchers said Saturday.
A simulation by a group of researchers led by Fumihiko Imamura, professor of tsunami studies at Tohoku University, found that a "resonance phenomenon" may have increased tsunami heights at six places in Iwate, Miyagi, Aomori and Fukushima prefectures. Tsunami in those areas may have been as much as three times higher than those that ravaged other areas on the Pacific coast.
Tsunami can be amplified when their frequencies match certain features of the coast, such as shape and depth — especially where coastlines are deeply indented. This phenomenon occurred at Ofunato Bay in Iwate Prefecture, when tsunami triggered by a major quake in Chile hit the area in 1960.