Paleotsunamis in Taiwan

Abstract:

Sitting between the Ryukyu and Manila subduction systems, Taiwan is among the world's most tectonically and seismically active areas. However, unlike Japan (from Hokkaido to the southernmost tip of Ryukyu), Taiwan is not known for tsunami events. Historical documents and folklores in Taiwan show a couple of records with different degree of certainty of tsunami, yet very few researches were conducted in paleotsunami researches.

During the past two years, we have conducted detail field surveys in Taiwan, and in several chosen area we have conducted shallow bore holes, trench excavations, and following geological and geomorphological researches. Our data show that northern Taiwan has been affected by tsunami both on and off historical records, and could be as many as 8 events. In eastern Taiwan, there are three probable tsunami events, and in western Taiwan, three or four inudation events were discovered that have features very similar to tsunamis.

In addtion to continuing field survey, we are performing numerical modeling based on the newly discovered geological evidences. The purpose is the reconstruct the processes of events and find the possilbe sources.