Abstract: In order to monitor the activity of Tianchi Volcano in the Changbai Mountains,a comprehensive geodetic monitoring network consisting of precise leveling and GPS stations,has been established since 2000.In this paper,we first introduce the installation of the geodetic network and then discuss the deformation results around the volcanic area. The results show that from 2002 to 2005,obvious ground deformation occurred in the Tianchi volcano area in the Changbai Mountains.In the vertical direction,the cumulative elevation difference of leveling line reached 6.8cm in the 3 years,and the nearer to the crater,the greater the deformation was.In the horizontal direction,centered on the crater,the observation stations showed a radial displacement in general,with the maximum up to 38cm.Significant expansion occurred in the mountains,and the maximum surface expansion was up to 6?10^-6/a.After 2006,these changes resumed to normal gradually.In the meantime,the Tianchi volcanic area of Changbai Mountains saw frequent volcanic seismicity,and other monitoring data also showed abnormal changes synchronously. The paper analyzes and discusses the possible reasons for these changes,and concludes that these changes may be the result of the latest magmatic activity of Tianchi volcano.

Key words: Tianchi volcano, precise leveling, GPS, crust deformation

摘要： 自2000年以来,在天池火山区附近布设了由2条精密水准路线、15个GPS测量点构成的地壳形变监测系统。文中详述了该系统的构成,并对近期长白山天池火山区地壳形变资料进行了分析研究。结果表明:2002—2005年,长白山天池火山区地面发生了明显的变形。在垂直方向上,水准路线高差3年累积变化达6.8cm,且越是靠近火山口,变形量越大。在水平方向上,以火山口为中心,各观测点总体位移出现放射状变化,最大可达38cm;山体出现明显的膨胀,最大面膨胀可达6×10^-6/a。上述变化于2006年后逐步恢复为正常变化。在此期间,长白山天池火山区火山地震活动频繁,其它监测资料也出现了同步的异常变化。文中分析讨论了引起上述变化的可能原因,认为是天池火山一次最新的岩浆活动所致。

关键词: 天池火山, 水准测量, GPS, 地壳变形