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High-precision Chronology of Eruptive Products during the Post-caldera Stage of Towada Volcano, Northeast Japan

2007; Taylor & Francis; Volume: 116; Issue: 5 Linguagem: Inglês

10.5026/jgeography.116.5_653

1884-0884

Takashi Kudo, Hisashi Sasaki,

earthquake and tectonic studies

Towada volcano is an active caldera volcano located at the northern part of the Northeast Japan arc. We re-examined the tephra stratigraphy of the post-caldera stage (15 ka to present) of Towada volcano, and carried out AMS radiocarbon dating of six soil samples taken from directly below the tephra layers. The most suitable ages of eruptive episodes A, B, C, D, D', E, F, G and Ninokura Scoria are estimated to be 1.1, 2.8, 6.2, 7.6, 8.3, 9.4, 10.1, 10.6, and 11-15 ka, respectively, on the basis of the thickness of soil layers between tephras and the radiocarbon ages determined by present and previous studies. This result shows that the eruption intervals have become longer with time, and the frequency of eruptions has decreased with time. Although the cause of this change is not known as yet, these are important data for predicting long-term eruptive activity of Towada volcano.