应用形变和重力资料分析腾冲火山区岩浆的活动特征  

ANAYSIS OF THE CHARACTERISTICS OF MAGMA ACTIVITY BASED ON THE DEFORMATION AND GRAVITY MEASUREMENTS IN TENGCHONG VOLCANO REGION

作　　者：胡亚轩[1] 王雄[1] 

机构地区：[1]中国地震局第二监测中心,西安710054

出　　处：《地震地质》2009年第4期655-663,共9页Seismology and Geology

基　　金："十一五"国家科技支撑计划项目(2006BAC01B020103)资助

摘　　要：文中对腾冲火山区1998—2004年水准及重力观测资料进行了分析,发现垂直形变量大多在±10mm之内,重力变化为几十μGal,火山锥体和断层附近点位活动异常较大,可综合应用多源mogi模型和断层模型解释,断层的活动可使相邻测点的形变方向相反;垂直形变和重力的逐年变化表明火山岩浆处于一种活动状态。将火山区点位各时间段的重力梯度展布在形变-重力关系解释图中,发现数据主要落在Ⅰ、Ⅱ、Ⅳ和Ⅴ区,结合形变量对压力源等效体积的估算,初步认为火山区岩浆目前活动程度较低,暂没有喷发的危险。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 of μGal. 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-Ⅳ）. If data are plotted in regions I or IV,both reflecting mass decrease and density decrease,volcanic eruptions are unlikely to occur as voids are created during this process. Data falling in regions Ⅱor Ⅴ （mass increase/density increase）reflect replenished magmatic system. Volcanic eruptions are unlikely to occur if the gradients plot is in region V,due to the lack of overpressure. Region Ⅱ may 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 regions Ⅰ , Ⅱ , Ⅳ and Ⅴ , 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 there is no danger of eruption We preliminary conclude that the magma activity is low currently and temporarily.

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 

分 类 号：P317.6[天文地球—固体地球物理学]