2:00 PM - 2:15 PM
[SSS08-19] A new representation and extraction method of marine terraces — application to the Numa terraces in the Boso Peninsula, central Japan
Keywords:paleo earthquakes, marine terraces, digital elevation model, Sagami trough, Kanto earthquakes
We applied this method to the Numa terraces, distribute along the coast of the southernmost part of the Boso Peninsula, central Japan. The Numa terraces are believed to be formed by 1703 the Genroku Kanto Earthquake (M8.2) and the interplate earthquakes of the same magnitude that occurred in the past 10,000 years. We confirmed that four paleo-shorelines of the southernmost part of the Boso Peninsula are successfully described on the elevation view. Moreover, this result lead to determine the relative heights between each of the Numa terraces,
Comparing the relative height distributions of the extracted paleo-shorelines, each terrace commonly has the average heights of 5 to 6m and has a trend that increasing toward southwest. On the other hand, there are some variations in the elevation difference between the east and west coast. Comparing the result of our study with the dating result measured at the Chikura lowland on the east coast [Komori et al., 2017, EPSL], the average relative heights that do not have much difference with each other is not consistent with the formation intervals of the Numa terraces which have a variation of three times or more at maximum.