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

白头山火山位于中国与朝鲜交界处，是世界上最活跃的火山之一，被称为10世纪大喷发。我们的研究旨在阐明这场10世纪喷发的细节及其对周围地区的历史影响。为此，我们通过对中国地区的实地考察，研究了火山产物的地质和岩石学特征。此外，我们还对朝鲜、中国和日本现存的历史文献进行了重新审查。这项研究新发现了以下几点。(1)10世纪火山喷发由两个小休眠的喷发期组成，在很短的时间内发生了两次巨大的褐沸石喷发。(2)发现了迄今未知的9世纪喷发。这次新的喷发有可能影响了渤海王朝的灭亡。(3)根据年代学和文献考证，10世纪喷发年龄为公元938年左右。(4)“镇废”分布图与10世纪喷发喷出物面积吻合较好。据认为，这意味着这次大喷发造成的灾区。

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.