1968年十勝沖地震と1978年宮城県沖地震の地盤災害および新興都市の地震災害予測

概要

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Ground failures and accompanied disasters in the eastern part of Aomori Prefecture and Miyagi Prefecture, both in northeastern Honshu, Japan, associated with the Tokachi-oki Earthquake of 1968 and Miyagiken-oki Earthquake of 1978, respectively, are outlined. Prediction of disasters by ground failures to be inflicted by the first strong schok in recently urbanized areas is possible on the basis of the geological observations in the above shaken areas. Failure of artficial fills may damage the overlying towns recently developed. Most dangerous areas are over the fills of upside-down type and of pyroclastic materials, which were constructed in the early phase of recent urban sprawl and have not been intensely shaken by earthquake yet. Shock may be amplified in the towns expanded over unconsolidated deposits of back marsh and abandoned river channel in the fluvial and coastal plains. Shock may efface the ground reclaimed from the river and sea, especially by sand and clay pumped up from the bottom of water, which are most suitable materials for liquefaction of the ground at the strong shocks. Failure of natural and artificial slopes by shocks may destroy the constructions close by them. Impatient urban sprawl rushed the open spaces left near the slopes.
日本地質学会の論文