Global Models of Surface Wave Group Velocity
Global Models of Surface Wave Group Velocity
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DOI：
10.1007/pl00001226
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发表时间：
2001-08
影响因子：
2
通讯作者：
E. Larson;G. Ekström
中科院分区：
文献类型：
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作者：
E. Larson;G. Ekström
群速度的测量来自相速度色散曲线和全球横向变化的各向同性结构建模。地图的爱和瑞利波的周期范围内创建35秒至175秒。群速度测量数据集包括50 000多个小弧观测和5 000个大弧观测。通过比较成对相似路径的经验方法来估计测量中的误差，从而导致典型测量的大小的20%至40%的不确定性。该模型是由最小二乘反演球谐映射扩展到40度。这种参数化可以分辨小至500公里的结构。相对于初步参考地球模型（PREM），这些模型解释了70-98%的方差。对于欧亚大陆，本研究的群速度图与RITZWOLLER和LEVSHIN（1998）的群速度图进行了比较。这两项研究的结果非常一致，特别是在空间相关性方面。这些模型在波长大于30度时的振幅也是一致的。对于较短的波长，协议是好的，只有在短时间内的模型。全球地图对于预测群到达时间、揭示构造结构、确定地震事件位置和震源参数以及作为区域群速度研究的基础都很有用。
Measurements of group velocity are derived from phase-velocity dispersion curves and modeled with global laterally-varying isotropic structure. Maps for both Love and Rayleigh waves are created in the period range 35 s to 175 s. The data set of group-velocity measurements includes over 50,000 minor-arc observations and 5,000 major-arc observations. The errors in the measurements are estimated by an empirical method of comparing pairwise-similar paths, resulting in uncertainties which are 20% to 40% of the size of the typical measurement. The models are determined by least-squares inversion for spherical harmonic maps expanded up to degree 40. This parameterization allows for resolution of structures as small as 500 km. The models explain 70–98% of the variance relative to the Preliminary Reference Earth Model (PREM). For the area of Eurasia, the group-velocity maps from this study are compared with those of RITZWOLLER and LEVSHIN (1998). The results of the two studies are in very good agreement, particularly in terms of spatial correlation. The models also agree in amplitude at wavelengths longer than 30 degrees. For shorter wavelengths, the agreement is good only for models at short periods. The global maps are useful for prediction of group arrival times, for revealing tectonic structures, for determination of seismic event locations and source parameters, and as a basis for regional group-velocity studies.