Journal of Natural Disaster Science

REGIONAL CHARACTERISTICS OF TSUNAMIS ALONG PACIFIC COAST OF HOKKAIDO*

Susumu TAKAHASHI
Associate Professor, Department of Engineering, Hokkaido University, Sapporo
and
Isao YAKUWA
Professor, Department of Engineering, Hokkaido University, Sapporo

(Received 14 November, 1979 and in revised form 28 December, 1979)

Abstract

On the basis of analyses of wave motions recorded at Hanasaki, Kushiro, Tomakomai, Muroran and Hakodate along the Pacific Coast of Hokkaido in Japan, regional characteristics of tsunamis are investigated. Tide gauge records in ordinary times and in four typical tsunamis : Tokachi-oki (1952, 1968), Chilean (1960) and Off-Nemuro Peninsula (1973) are analyzed. From the results of power spectral analyses of the records, peaks of spectra in ordinary times are amplified in tsunamis and the predominant period is elongated as the magnitude of the earthquake increases. Dominancy of oscillation modes is different with each gauge station because oscillation systems vary locally.

Key words

tsunami, period of seiche

* Part of this work was published in the Journal of Analytical Researches on Data of Natural Disaster, Vol.3, 1976 (in Japanese).