【作者】 王小平；

【导师】 朱元清；

【作者基本信息】 同济大学 ， 固体地球物理， 2007， 博士

【摘要】 华东地区，特别是下扬子-南黄海地区，是我国一个重要的中强地震活跃区。作为上海及其邻近地区这个特殊地带，位于长江三角洲，属于下扬子地块，是我国经济发展战略要地之一，这是一个城市高度集中，人口十分稠密，经济建设蓬勃发展的黄金地带，但同时也是地壳构造十分复杂，天然地震相对比较活跃和中强地震频度较高的地带，具有人口高度集中、高楼林立等特点。作为一个中强地震多发的地区，并包含几个特殊结构，如郯庐断裂、茅山断裂、萧山-球川断裂等，分析其地壳结构的基本特征，查明其深部构造的背景在地震监测、地震预报和工程地震等研究方面，具有理论意义和实际应用价值。本论文主要做了以下几方面的研究工作：首先利用层析成像方法对上海及其邻近地区进行了地壳P波、S波的速度反演，从而得出该地区的速度扰动图，并给予了中肯的解释。在对有关远震波形资料的利用、接收函数发展历史、提取、反演和叠加方法的原理比较了解的基础上，调试了接收函数提取及反演的有关程序。参照Dueker等人1997年的共转换点叠加方法，调试编制了间断面的叠加程序。这里研究了从2002年到2004年底江苏、上海、浙江地震监测台网的台站所测得的远震资料，经过地震挑选截取、滤波，最后提取接收函数。对每个台站的接收函数进行挑选，去掉质量不高的接收函数，叠加质量较高的接收函数，这样就得到了42个台站的接收函数的径向分量和切向分量。反演接收函数的径向分量，得到每个台站下方的一维S波速度结构。结合该地区深地震测深资料，分析每个台站下方的速度结构，认为S波速度发生突变，其数值达到为4.3km／s所对应的深度为Moho面所在位置。研究表明，江苏地区地壳构造复杂，特别是地壳内存在低速层，该地区的地震可能与深部构造背景有关，也可能与地壳构造的复杂程度有密切关系，特别是地壳中的低速层及高导层的存在关系密切。宿迁、溧阳、温州，这些台站具有地震活动频繁外，具有较高的泊松比、复杂的地壳速度结构，这一特征与周边地区存在明显的差别。周边地区基本呈现在弱震区或稳定块体内部，有较低的泊松比，而在宿迁、溧阳、温州等易震区具有较高的泊松比。对243个接收函数进行了滤波处理，采用IASP91模型，计算了各个接收函数在33km、410km和660km叠加深度上转换点位置。在对叠加测线上的共转换点进行动校正后，用100km为半径的共面圆进行共转换点叠加，从而得出研究区域内410km间断面的平均深度为(410km±20km)；研究区域内670km间断面的平均深度为(670km±10km)；剖面1上410km间断面及660km间断面比较清晰，沿经度自西向东，位置逐渐加深。最后研究了基于PpSms、p660S及SKS震相研究上海地震台阵下方的各项异性随深度的分布情况，同时利用接收函数的PS转换波研究该地区地壳下方的各项异性情况，从而得出各向异性参数及大致分布范围。更多还原

【Abstract】 The East China, specially the lower Yangzi-South Yellow Sea area is the importantstrong and active earthquake area in our country.Shanghai and its neighbour area arelocated in the Yangtze River delta.It belongs to the Yangzi land parcel and is one ofone of our country economic development strategy important places.This is an area ofmany economic developed cities with high density of populatiion.But an extremelycomplex structure of earth’s crust is under it and natural earthquakes are relative quiteactive,even sometimes strong earthquakes occured.It has the following characteristicsin this area:the great number of tall buildings and so on.As the area is in theory, it hasthe significance and the practical application value to analyze its earth’sstructure,verify the background of its deep structure in earthquake monitor, earthquakeprediction and project earthquake.This present paper has mainly done followingseveral aspects in the research work:First we inverse crust P wave and S wave velocity structure under shanghai and it’sneighbor area using seismic tomogrphic image method,and we get this area velocityperturbation,then we give the critical explanation.On the basic of better understanding about how to use teleseimsic waveform and ofknowing about receive function development history, extraction,inversion and stackprinciple methods,we have debugged the receive function extraction and inversion re-lated procedure.Referred to the Commom Conversion Point Stack method which wasbrought forward by Dueker et al. 1997,we debugged the stacking programme about h-ow to get the discontinuity.Here we has collected some teleseismic events which were observed byjiangsu,shanghai and zhejiang seismic network since 2002,then we selected,filtered,at last wegot receiver functions.We selected these receiver functions,removed those bad qua-lity receiver functions,stacked these good quality receiver functions,then we get radialcomponent and tangential component receiver functions about 42 seimic stations.Aft- er inversing radial receive functions,we got 1D crust S wave velocity structure underthese stations.Combining local deep Seismic Sound information,we analyzed velocitystructure under every station,then we think that s wave velocity change suddenly atthe depth of Moho surface and get up 4.3km/s.The result shows that the cruststructure under jiangsu province is complex,inscipally there exist low velocitylayer.The earth-quakes maybe be related to complexity about deep crust structure background,or berelated to the complex degree about deep crust structure, especially be closely relatedto low velocity layer and high conduct layer.The poisson’s ratio is a little high in Suqian,Liyang,Wenzhou.In these areas,thepoisson’s ratio is higher,the seismic activity frequently is high and there has the com-plex earth’s crust speed structure. This characteristic is obviously different from theneighbor area.It basically presents that the poisson’s ratio is lower in the weak earth-quake area or stable block body,but the poisson’s ratio is higher in earthquake pronezone.We process these 243 receive functions by filtering and calculate the conversionpoint at 33km,410km and 660km stack depth for every receiver function.After dyna-mic correction for common conversion point at stacking line,we use 100km as radiusfor stacking and get the result that the average depth of 410 and660 discontinuity isabout 410±20km and 670±10km respectively.The 410 and 660 discontinuity underProfile 1 are clear comparatively, along the longitude from west to east, the positiongradually deepens.At last we have done the anisotropy distributed situation under shanghai seismol-ogical array stations with the depth which is based on PpSms, p660S and the SKSphase.Meanwhile we analyze the distribute about anisotropy reader this area crust usi-ng using the receive function PS converted wave, thus obtain the anisotropic parame-ter and approximately the distributed range.更多还原