Abstract:

A digital elevation model(DEM)is a digital representation of terrain surface morphological attributes, describing ground relief with spatial position and terrain characteristics. With advancements in technology, particularly increased satellite data acquisition capabilities, accurate high-resolution DEMs have become crucial in volcanology research, especially in remote regions. The Tengchong volcanic field, one of China’s prominent young volcanic groups, has experienced Cenozoic volcanic activity from the Pliocene to the Holocene. Recent monitoring and studies indicate that three Holocene volcanoes—Heikongshan, Dayingshan, and Maanshan—pose potential future eruption risks. The volcanic activity of these three Holocene volcanoes has garnered significant attention. This paper focuses on the Heikongshan volcano in the Tengchong volcanic field of Yunnan Province, China, using DEM visualization technology to generate rendered topographic maps and optical images of the volcanic area. We interpret and analyze the volcanic landforms, summarizing the geomorphic characteristics of different volcanic cones, lava units, and lava flow features formed during eruptions. By comparing the spatial distribution of lava units over different periods, we observe that newer lava units accumulate on older ones, exhibiting distinct morphological patterns in tomography. The distribution range of lava at different periods is clearly stratified. Our study proposes a reliable approach to mapping lava units, complementing traditional mapping methods in regions with thick forest cover. We complete the zoning map of lava flow units in the Heikongshan volcanic area using DEM maps. Compared to traditional volcanic geology mapping methods, DEM-derived boundaries of lava flow units are more accurate and less affected by challenging field observation conditions. Based on the DEM model and previous geological survey results, we classify Heikongshan’s eruptive activities since the Pleistocene into four stages, each with varying coverage areas. The early lava flows(Phase I)were primarily distributed north of the Heikongshan cone, extending eastward in a tongue shape. Middle-stage active lava flows(Phase Ⅱ)were mainly around the cone. In the late period, the activity’s scale and scope decreased, with small-scale tongue-shaped lava flows moving eastward(Phase Ⅲ)and small-scale sheet flows moving northward(Phase Ⅳ). Our findings provide volcanic geomorphic evidence for understanding the eruption history and offer insights into historical volcanic hazards. This information is valuable for volcanic disaster assessment and hazard evaluation in the future.

Key words: Heikongshan volcano, Tengchong volcanic field, DEM, Volcanic morphology, Lava flow unit

摘要：

随着科学技术的发展, 卫星能力和数据技术的不断提高, 高分辨率遥感数据在火山学研究领域, 尤其是在人类活动难以涉及的无人区的火山研究中起到了越来越重要的作用。文中以云南腾冲火山区黑空山火山为例, 进行了DEM数字高程试验性研究, 利用DEM模型可视化技术获得了黑空山火山区渲染地形图和光学影像, 解译并分析了研究区内的火山地貌, 总结了不同类型火山锥、 熔岩台地的地貌特征, 以及熔岩流流动过程中所形成的特殊流动构造的地貌特点。以前人完成的黑空山火山区熔岩流单元分布为基础, 分析了不同期次喷发物在地形高度上的变化特征, 发现喷发年代越早, 分布距火口越远, 且坡度越缓, 高程越低。晚期喷发物往往堆积在早期喷发物之上, 不同时期的熔岩分布范围有明显的层次性。在上述分析研究基础上, 首次利用高分辨率DEM数字技术完成了黑空山火山区熔岩流动单元区划图, 为理解黑空山火山新期喷发历史和喷发序列的恢复提供了很好的火山地貌证据。此外, 不同时期熔岩流的覆盖范围也客观反映出历史火山灾害的类型和影响范围, 为未来的火山灾害评估、 火山灾害区划图的编制提供了基础素材。

关键词: 腾冲黑空山火山, DEM模型可视化, 火山地貌, 熔岩流单元