Tsunami occurring prior to the historical record or for
which there are no written observations.

Paleotsunami research is based primarily on the
identification, mapping, and dating of tsunami deposits
found in coastal areas, and their correlation with similar
sediments found elsewhere locally, regionally, or across
ocean basins. In one instance, the research has led to a
new concern for the possible future occurrence of great
earthquakes and tsunamis along the northwest coast of
North America. In another instance, the record of tsunamis
in the Kuril-Kamchatka region is being extended much
further back in time. As work in this field continues it may
provide a significant amount of new information about past
tsunamis to aid in the assessment of the tsunami hazard.