Abstract: The recorded 1199~1200 A.D. eruption is the largest among all the Changbaishan volcano eruptions in history. It can be subdivided into two phases of Plinian eruption, the first is named the Chifeng phase and the second the Yuanchi phase. The eruptive pattern of the Chifeng phase is: Plinian column (the Chifeng pumice fall deposits) → pyroclastic flow (the Changbai pyroclastic flow deposits) → lahar (the Erdaobaihe lahar deposits) mainly triggerd by pyroclastic flow. The eruptive pattern of the Yuanchi phase is from Plinian column (the Yuanchi pumice and ash fall deposits) → pyroclastic flow (the Bingchang pyroclastic flow deposits). The total volume of both the first and the second Plinian falls has been estimated at about 120 km³. The bulk volume of the Changbai pyroclastic flow deposits was estimated about 8 km³; that of the Bingchang pyroclastic flow deposits about 0.5 km³ and of the Erdaobaihe lahar deposit about 2 km³. The author deals with mainly the sequence and distribution of the pyroclastic deposits of the 800 a.B.P. eruptions.

Key words: volcano eruption, pyroclastic deposits, Changbaishan volcano