Effective research method and problems of the Paleotsunami studies in Taiwan

Abstract:

Study on paleotsunami deposits in geologic stratum is one of valuable tools for identification of paleoearthquake in the tectonically active coast, including Taiwan.After the 2011 Tohoku tsunami, demand increased greatly for geologists with expertise in the geology of tsunami deposits, who could study prehistoric tsunami deposits.And, in Taiwan, showed in deep interest the study about the study on paleotsunam ideposits.

By the way, did the tsunamis ever attacked the east coast of Taiwan?According to ancient documents and oral transmission, in Taiwan, had the big tsunami event of three times in the past.As for the record of ancient documents, "the big wave" attacked the southwest district and northern part of Taiwan, but there are not the details.

In addition, ancient documents record does not have the tsunami record of the East Coast of Taiwan, but there is the tradition of "the big wave" by the native oral transmission in the East Coast of Taiwan.It may be related to the southern part of Ryukyu there attacked seven times of tsunami events during approximately 5,500 years.Although it was thought that the record of the tsunami had not attacked the tsunami only by indistinct ancient documents record and native oral transmission, we think that it is to be the tsunami study in the East Coast of Taiwan because there is an event in the southern part of Ryukyu.

Taiwan, especially along the east coast of the Coastal Range, is different,reaching a maximum uplift rate of 15 m/ka with 10 subdivided steps. They record a very rapid uplift.It is thought that it is difficult by the conventional study on paleotsunami deposits.

In a distinctive tectonic and morphologic in east coast of Taiwan, we consider what kind of study on paleotsunami deposits investigation is effective concretely.