用转换函数研究那木错站地壳结构

青藏高原是研究地球动力学问题天然的试验场,也是研究全球变化的关键地区之一,中国科学院青藏高原研究所于2004年在西藏那木错建立了圈层相互作用综合观测研究站.为了解那木错站下方的地质构造,于2005年8月在本站布设了宽频带地震仪(记录器为Reftek130,摆为STS2),并于2006年5月取得首批数据.本文利用宽频带地震仪提供的三分量地震波形记录,应用转换函数及快速模拟退火算法对那木错站下的地壳横波速度结构进行了反演.反演结果表明,那木错站Moho面深度在85公里左右,地壳结构复杂,尤其在中上地壳,明显呈高低速互层结构,反映了该地区构造活动、物质交换活跃,表明这些地区还未达到均衡;同时,为了便于研究该地区地壳结构,还对IRIS提供的临近地区的地震宽频带进行了处理,为研究那木错地区圈层结构提供地球物理依据.

A study of crust structure beneath NMCO seismic station using transform method

The Tibetan plateau is a natural lab for studying geodynamic and global environmental change.In 2004,a compositive observation station was established by The Institute of Tibetan Plateau Research for studying mutual effect between lithosphere,biosphere and atmosphere.For studying the crustal structure beneath the compositive observation station,a broadband seismometer(model is Reftek 130,pendulum model is STS2) was installed in Aug 2005 and gathered first dataset in May 2006.In this paper,according to three-componenets teleseismic records from broad-band seismometer,the S wave velocity structural beneath NMCO compositive observation station was investigated by using the transform function method and the simulated annealing techique.Our results indicate that,the Moho depth is 85km beneath the station and the crust structure is complex.Particularly,there is low-velocity and high-velocity interlock exists in upper or middle crust.It indicates that tectonic movement and substance exchange are active in the plate boundary regions where the crust remains in the state of imbalance.Also we processing the data provided by seismic station in adjacent region,all of those results will provide geophysics evidence for studying crust structure of this region.