关键词: 垂直形变, 重力变化, 联合分析, 岩浆活动特征, 腾冲火山

Abstract: Through analyzing the leveling and gravity data of 1998-2004 in Tengchong volcanic region,it is observed that the vertical deformation mainly concentrates in the range of±10mm and the variation of gravity is several dozens ofμGal.Those stations especially built in the volcanic cone and near the fault have big anomaly changes.The integrated application of Mogi sources and fault models can explain the observation data well.When the relative movement between the two walls of a fault in the surveying region happens,the rates of the sites on the different walls can be opposite.The variation of leveling and gravity data in different periods shows the magma in the volcano is active.The predicated gradients(FAG and BCFAG)divide the interpretation graph of Ag/Ah data into six regions(Ⅰ-Ⅵ).If data are plotted in regionsⅠorⅣ,both reflecting mass decrease and density decrease,volcanic eruptions are unlikely to occur as voids are created during this process.Data falling in regionsⅡorⅤ(mass increase/density increase)reflect replenished magmatic system.Volcanic eruptions are unlikely to occur if the gradients plot is in regionⅤ,due to the lack of overpressure.RegionⅡmay reflect potential persistent volcanic activity.Eruptions,if they were to occur,are likely to be effusive and/or low-explosivity events due to the lack of significant pressurization.The vast majority of data in Tengchong volcano fall in regionsⅠ,Ⅱ,ⅣandⅤ,so volcanic eruptions are unlikely to occur.The volume change of the volcanic edifice is estimated by deformation and it is also lower than that of the moderate explosive eruption.We preliminary conclude that the magma activity is low currently and there is no danger of eruption temporarily.

Key words: vertical deformation, variation of gravity, free air gradient, magma activity characteristics, Tengchong volcano