Abstract
Studies on the sediments induced by paleoseismic events, especially tsunami deposits, are reviewed and examined.
Various types of sediments with conspicuous characteristics are produced by paleo-seismic events. The following are typical examples of paleo-seismic events in the Holocene coastal sediments that have been studied: (1) Change in sedimentary environment caused by submergence or emergence; (2) Sedimentary structure change of intruded sandy sediments caused by seismic shaking, and re-concentration of heavy minerals in the sediments; (3) Re-sedimentation of marine and lacustrine deposits by gravity flow deposits such as turbidite and subaquatic landslide sediments; (4) deposition of tsunami deposits.
Synchronous and regional characteristics are the most useful ones for the identification of these events. Relatively coarser sediments such as sandy or gravelly layers with grading structure are characteristic of tsunami deposits. The deposits also become finer towards the inland, and a frame-like structure often can be recognized at the top contact with the under lain soft sediments. Microfossils and geochemical substances of marine origin sometimes increase at the horizons of tsunami deposits.
