地震学报
地震學報
지진학보
ACTA SEISMOLOGICA SINICA
2014年
5期
826-836
,共11页
面波%层析成像%背景噪声互相关%广东及其邻域
麵波%層析成像%揹景譟聲互相關%廣東及其鄰域
면파%층석성상%배경조성호상관%엄동급기린역
surface wave%tomography%ambient noise correlation%Guangdong and its adj acent areas
通过收集广东及其邻域104个固定地震台站近10个月的垂直分量连续波形数据资料,使用地震背景噪声互相关格林函数方法,获得了大部分台站对的背景噪声互相关曲线。基于这些对称叠加的互相关曲线,利用时频分析方法,进一步提取了该地区周期为5-40 s 的基阶瑞雷波群速度频散曲线。其噪声来源分析结果显示:广东及其邻域的噪声场来源有很强的方向性,短周期(5-10 s)噪声主要来自东南方向,范围基本与海岸线分布一致,可能是由于近海水陆相互作用产生的;较长周期(15-30 s)噪声主要来自三大洋的方位。以这些提取的噪声面波资料为基础,采用噪声面波层析成像方法反演得到了该地区周期为5-28 s 的瑞雷波群速度层析成像图,从该图可以看出,广东及其邻域地下结构的横向变化总体较小,沉积层厚度较薄,地壳中可能普遍存在一个低速层;从研究区历史地震的分布及其表层地质构造的发育特征来看,地震主要分布在高、低速过渡带附近,表明面波群速度与地震之间具有较强的耦合关系;从群速度的低速异常特征来看,广东及其邻域普遍分布的温泉和高地热主要受深部构造的控制和影响。
通過收集廣東及其鄰域104箇固定地震檯站近10箇月的垂直分量連續波形數據資料,使用地震揹景譟聲互相關格林函數方法,穫得瞭大部分檯站對的揹景譟聲互相關麯線。基于這些對稱疊加的互相關麯線,利用時頻分析方法,進一步提取瞭該地區週期為5-40 s 的基階瑞雷波群速度頻散麯線。其譟聲來源分析結果顯示:廣東及其鄰域的譟聲場來源有很彊的方嚮性,短週期(5-10 s)譟聲主要來自東南方嚮,範圍基本與海岸線分佈一緻,可能是由于近海水陸相互作用產生的;較長週期(15-30 s)譟聲主要來自三大洋的方位。以這些提取的譟聲麵波資料為基礎,採用譟聲麵波層析成像方法反縯得到瞭該地區週期為5-28 s 的瑞雷波群速度層析成像圖,從該圖可以看齣,廣東及其鄰域地下結構的橫嚮變化總體較小,沉積層厚度較薄,地殼中可能普遍存在一箇低速層;從研究區歷史地震的分佈及其錶層地質構造的髮育特徵來看,地震主要分佈在高、低速過渡帶附近,錶明麵波群速度與地震之間具有較彊的耦閤關繫;從群速度的低速異常特徵來看,廣東及其鄰域普遍分佈的溫泉和高地熱主要受深部構造的控製和影響。
통과수집엄동급기린역104개고정지진태참근10개월적수직분량련속파형수거자료,사용지진배경조성호상관격림함수방법,획득료대부분태참대적배경조성호상관곡선。기우저사대칭첩가적호상관곡선,이용시빈분석방법,진일보제취료해지구주기위5-40 s 적기계서뢰파군속도빈산곡선。기조성래원분석결과현시:엄동급기린역적조성장래원유흔강적방향성,단주기(5-10 s)조성주요래자동남방향,범위기본여해안선분포일치,가능시유우근해수륙상호작용산생적;교장주기(15-30 s)조성주요래자삼대양적방위。이저사제취적조성면파자료위기출,채용조성면파층석성상방법반연득도료해지구주기위5-28 s 적서뢰파군속도층석성상도,종해도가이간출,엄동급기린역지하결구적횡향변화총체교소,침적층후도교박,지각중가능보편존재일개저속층;종연구구역사지진적분포급기표층지질구조적발육특정래간,지진주요분포재고、저속과도대부근,표명면파군속도여지진지간구유교강적우합관계;종군속도적저속이상특정래간,엄동급기린역보편분포적온천화고지열주요수심부구조적공제화영향。
We obtain the ambient noise cross-correlation curves for most of the station-pairs using 10 months of continuous data from the 104 permanent seis-mic stations of the Guangdong seismic network and its surrounding regions. Based on these symmetrically superimposed cross-correlation curves,we com-plete Rayleigh wave group velocity dispersion measurements for the periods from 40 s down to about 5 s using time-frequency analysis method.Ambient noise source analyses show that in Guangdong and its neighbor areas,sources of noise field has a strong directionality.Short-period noise (5-10 s)is mainly from the southeast,and its distribution is consistent with the scope of the coast-line,so it may be caused by interaction of coastal land and water.Longer-period noise (15-30 s)mainly comes from the orientation of the Pacific,Atlantic,In-dian Oceans.Furthermore,we obtain the Rayleigh wave group velocity distri-bution maps in the whole studied area for the periods from 5 s to 28 s using the ambient surface wave tomography algorithm.The tomographic results revealed that in Guangdong and its adjacent areas the crustal lateral variation is small, and the surface sediment thickness is thinner,indicating that there may be a widespread low-velocity layer in the crust.According to the characteristics of history earthquakes and surface geological structure,it can be obtained that earthquakes are mainly distributed in the vicinity of high- and low-velocity tran-sitional zone,suggesting there is a strong coupling relationship between surface wave velocity and earthquakes.From low group velocity anomaly,it is inferred that the high geothermal and hot springs widely distributed in Guangdong and its neighbor areas is mainly under the control and influence of the deep structure.