History of Eruptions and Volcanic Damage from Sakurajima Volcano, Southern Kyushu, Japan

Abstract

Volcanic damage caused by the four largescale eruptions of Sakurajima volcano in historic time is first outlined, and then, on the basis of the eruptive history, the damage in prehistoric time are also summarized. Not only large-scale eruptions but also intermittent vulcanian eruptions have been identified.
The sequence of large-scale eruption was as follows: first, precursory phenomena; second, the beginning of plinian eruption; third, generation of pyroclastic flows and surges; fourth, outpouring of lava flows; and finally, broad subsidence of the ground after the eruption. Such large-scale eruptions occurred 17 times (-19 times), and the ca. 11 ka P14 eruption was the largest among them; the erupted volume of P14 was about 11km³, causing severe damage all over the southern Kyushu. The P13, which overlies the Uenohara remains, was the second largest tephra (1.3km³). Due to the heavy ash fall, settlement in the area was estimated to be difficult for some years after the eruption.
Large quantities of fallen ash from the plinian eruption not only buried farms and houses but also became the generating factor of lahars for a few years. Many lahars occurred especially in the region mantled by ash more than 30 centimeters thick. Vulcanian eruptions did not cause any volcanic disasters around the periphery of Aira caldera, but caused many lahars in Sakurajima Island during heavy rains.
In order to reduce the volcanic hazard, it would be necessary not only to intensify hard countermeasure but also to conduct careful hazard mapping and disaster prevention education.