Remote-sensing Based Analysis On The Types And Process Of Lava Flow In Huoshao Mountain,Wudalianchi Volcanic Field

Volcanic eruption is a natural phenomenon that has existed since the formation of the earth.Volcanism is an indispensable basic geological process in the formation and evolution of the earth,and also provides an important basis for the development of modern material civilization.The study of volcanic eruptions and disasters is not only of great academic value,but also of great practical significance to the development of resources,environmental protection and the sustainable development of human society.The study area is the Huoshao Mountain in northeast china,which is located in the volcanic area of northeast china and is an important volcanic research area in china and even the world.Lava flow of Huoshao Mountain is the latest lava flow formed by the eruption in domestic records.The lava covers an area of 70km2,and the volume of the lava flow accounts for 90% of the total volume of its eruption.In addition,the condition of the crust is well preserved,the vegetation coverage rate is low and the quaternary volcanic and geological activities in the area of Huoshao Mountain are very strong,so there is a potential risk of eruption.The volcanic cone of the Huoshao mountain is lower than others in Wudalianchi where jet cones,jet disks and lava tunnels are widely distributed.Considering that this research needs high-precision Digital Elevation Model and Digital Orthophoto Map in the Huoshao Mountain,two methods,including unmanned aerial photography and field exploration,are adopted for this field work.The obtained land surface photos were stitched together by using photoscan and ArcGIS software.The data processing flow and the inversion of eruption process are taken as the research ideas,that is,for the lava flow unit,the lava flow boundary and the types of lava flow surface shell are mainly divided.By using ArcGIS software,the surface crust elements of lava flow are quantitatively divided according to roughness's calculation and then measure the area and the thickness in the field and restore the eruption volume.Finally,according to the historical records,the kinetic parameters such as the average lava overflow rate and the average velocity are recovered.Considering the requirement of high-precision Digital Orthophoto Map and Digital Elevation Model,I use the photoscan and ArcGIS software splicing and integration of the proceeds of the unmanned aerial vehicle(UAV)photos in two ways and generate the surface photos;Inversion of data processing process and eruption process is the research idea,that is,for lava flow units,focus on dividing lava flow boundaries and types;Using ArcGIS software,the surface shell units of lava flow are quantitatively divided according to roughness calculation.And then,I measure area and thickness in the field,and restored eruption volume.Finally,according to the historical records,the average lava overflow rate and average velocity are restored.Based on real-time tracking and measurement data of the lava flow during the eruption of Holuhraun volcano in Iceland,this study divides the surface crust of the lava flow in the Huoshao Mountain into aa flow,slabby pahoehoe and spiny pahoehoe.According to the geological map of Laohei Mountain and Huoshao Mountain drawn by Bai Zhida et al in 1999,I draw the lava flow phase diagram and lava flow flow route.In ArcGIS,the area of the lava flow in the Huoshao Mountain is 21.0873km2 by using the geometric calculation tool in the attribute table.The bottom of DEM is clipped,the heights of all DEM points are calculated,and then the average thickness of Huoshao Mountain lava flow equals 22.4m which is obtained by dividing the number of points,and the volume is calculated to be about 0.472km~3.According to the study on Manchu archives related to Wudalianchi volcanoes,it is concluded that the eruption time of Huoshao Mountain was around April 26,solstice June 21,1721 ad,with a total of 56 days.According to the study on the recovery of flow velocity and overflow rate of Jinlongdingzi volcano and the empirical formula of the relationship between the length of crust lava flow and the average overflow rate put forward by Pinkerton in 1994,the average overflow rate and flow rate of lava flow during the 1721 eruption in the Huoshao Mountain area are calculated and tested.In addition,according to the formula,the destruction index at the outbreak of Huoshao Mountain in 1721 is restored.The research is mainly reflected in the study of the digital rapid division of the surface crust types of the lava flow in the Huoshao Mountain,the restoration of the flow process of the lava flow,and the study of the dynamic parameters.As the latest eruptive lava flow in china,the lava flow of Huoshao Mountain provides excellent resources for domestic volcanology research.this research not only discusses the basic eruption process of Huoshaoshan volcano,but also provides some technical tools for the later study in this area and even other volcanic areas.