Joint study among Japan, China and Korea, about Baitoushan volcano in Northeast China, its magma history and the 10^<th> century big eruption

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Baitoushan volcano, situated on the border between China and North Korea, is one of the most active volcanos in the world, and is known by the 10^<th> century big eruption. Our research intends to clarify the details of this 10^<th> century eruption and its historic effects on the surrounding area. For this purpose, we have investigated geological and petrological features of the volcanic products by the field survey on the Chinese area. In addition to this approach, we made the reexamination of the historic documents existing in Korea, China and Japan. The following things have been newly found by this research. (1)The 10^<th> century eruption consists of two eruptive phases with minor dormancy, and the two times of huge ignimbrite eruption have occurred at the very short period. (2)The 9^<th> century eruption, which wasn't known so far, was found. It has possibility that this new eruption has affected the extinction of Bo-Hai dynasty. (3)The 10^<th> century eruption age is around AD 938, based on the chronological study and literature research. (4)The distribution map indicating the "Abolishment of Township" is good agreement with the area of 10^<th> century eruption ejecta. It is considered that this implies the disaster area induced by this big eruption.