Eruption Age of Sakurajima-Satsuma Tephra Using Thermoluminescence Dating

Sakurajima, located on the southern volcanic front in Kyushu, is a very active volcano in Japan. Tephra beds from Sakurajima volcano are collectively designed as the Sakurajima-tephra (Sz) group (Kobayashi, 1986). The eruption history of Sakurajima volcano is classified tephrostratigraphically into the following three stages: Old Kitadake, Young Kitadake, and Minamidake (Kobayashi and Ezaki, 1997). The first eruption of the Young Kitadake stage is designated as Sakurajima-Satsuma (Sz-S or P14) tephra (Kobayashi and Ezaki, 1997), which is volcanic ash of the largest eruption of the Sz group (e.g. Moriwaki, 1992). Sz-S derived from Sakurajima volcano is a key marker for volcanic stratigraphy, palaeoenvironmental studies (e.g. Moriwaki, 1992), and archaeological studies (e.g. Kodama, 2001) in southern Kyushu and surrounding marine regions of Sakurajima volcano because this tephra, with the largest volume (ca. 11 km: Kobayashi and Tameike, 2002) of Sakurajima tephras, is widespread throughout southern Kyushu. Therefore, age determination of this key tephra layer (Sz-S) is expected to contribute greatly to studies in many fields. Regarding the ages of Sz-S, Machida and Arai (1992) reported a radiocarbon (C) age of 10,500 BP as an average of several charcoal ages obtained using the beta counting method. Okuno (1997) obtained accelerator mass spectrometry (AMS) C ages of charcoal samples from tephra beds of Sz group, and soil materials related closely to the tephra. The reported C ages are presented in Table 1. Okuno (2002) estimated it as 12,800 cal yrBP based on the C dates shown in Table 1. Eruption Age of Sakurajima-Satsuma Tephra Using Thermoluminescence Dating