Changbaishan Volcanos: Volcanostratigrapy, volcanic architecture and their linkage with eruption trend analysis and hazard prediction

Time:	2015-2018
Fund:	860 Thousend Yuan
Project No.:	41472304
Type:	NSFC
Leader:	Pujun Wang
Participant:	Pujun Wang,Xikui Wang,Chengzhi Wu,Chongyang Chen,Jian Yi,Yanquan Wang

Similar to a skyscraper volcano can be described by their basic composing units (volcanostratigraphy) and architecture. As inherent attribute volcanostratigraphy and volcanic architecture have their own characteristics and evolution rule that provide us with incomparable clues to the trend analysis of volcanic eruption. They also impact on stability of the accumulated building and thus on the forms of related volcanic hazard. But little have been researched about them up to now. Changbaishan are dormant
volcanos that may erupt at any time in the near future. Many of the lava volcanos sit high on the soft Quaternary/Neogene sediments. The unstable architecture coupled with large amount of low density pumice (<1 g/cm3) deposits are prone to resulting in secondary calamities like landslide, slump, and re-transported pyroclastic flow. The project design to study 19 well exposed volcano outcrops, measure 2 grand-canyon sections of more than 30 km long each, and re-process the data of pre-existing petroleum/geothermal boreholes, ground precision magnetic survey, and natural seismographic network. Large scale mapping work will be carried out for several selected key squares in the region. We will focus on the volcanic stratigraphic unit, boundary, and stacking pattern in order to not only highlight every single component but also to get comprehensive recognition of different volcanos. Volcanic architecture concerning landscape, construction of the main body, and structure of the feeder systems will be also studied by means of integrated geological-geophysical technique. There are about 18 eruption cycles since Oligocene in the area. Volcanic stratigraphy, boundary, architecture, and ejected component and composition will be counted in detail for each of the cycles to get the time and space sequence of the volcanos. We hope that the statistic results may tell us some of the potential features of next eruption. Primary and secondary boundaries of the volcanostratigraphy will be specially emphasized in the above sequences because the latter indicate re-transportation of the previously accumulated materials in geological history and thus a kind of \"hazard\" could happen in the past. They may be indicative of a past landslide, debris avalanche, joekullaups, and so on. This kind of past events can be revealed by unconformable contact surfaces between different volcanic members, i.e. secondary boundaries. Such ancient and historical recorded volcanic hazards will be addressed to the category and characteristics of the volcanostratigraphy and volcanic architecture, so as to establish the linkage between hazard characteristics and volcano natures. Potential natural disasters and their consequences related to the widely distributed volcanos will be suggested according to their presently seated situation, which can be used as a scientific guidance for the disaster prevention and mitigation engineering of the district.