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基于背景噪声的宁夏及邻区瑞利波层析成像
谢辉,马禾青,马小军,李青梅,张楠,任家琪
作者单位
谢辉 宁夏回族自治区地震局, 宁夏银川 750001 
马禾青 宁夏回族自治区地震局, 宁夏银川 750001 
马小军 宁夏回族自治区地震局, 宁夏银川 750001 
李青梅 宁夏回族自治区地震局, 宁夏银川 750001 
张楠 宁夏回族自治区地震局, 宁夏银川 750001 
任家琪 宁夏回族自治区地震局, 宁夏银川 750001 
摘要:
使用了宁夏及邻区90个地震观测台站资料,反演得到了该区高分辨率的瑞利面波层析成像结果。选用2012年1月至2013年12月的垂直分量连续波形数据,通过对台站对间进行波形互相关和叠加运算,得到各台站对间的经验格林函数,使用 CPS(Computer Programs in Seismology)软件测量得到了4005条瑞利面波群速度频散曲线。选取信噪比大于10的经验格林函数对频散曲线进行了筛选,提取了3182条台站对间的频散曲线,反演得到了研究区周期6~50s,分辨率达0.5°×0.5°的瑞利波群速度分布图像。银川盆地在6~26s为明显的低速异常,且盆地内部的低速异常呈现出不均匀的减弱趋势;关中盆地在6~22s为条状低速异常,呈现出东南部的速度略强于西北部的横向不均匀性;在30~50s呈现出在银川断陷盆地及其以南存在一自北东向西南走向的大区域低速异常区,且表现出山地与盆地之间的主要活动构造带存在明显的地貌界线,即六盘山附近的深大断裂是中国东西两大构造单元的分界线。反演结果与研究区地质构造特征、地层地貌具有较好的相关性,且和银川盆地与穿过盆地的人工地震剖面结果吻合,为该地区活动构造带的动力学和强震发震机理研究提供重要依据。
关键词:  背景噪声  面波层析成像  地壳上地幔  宁夏及邻区
DOI:
分类号:
基金项目:
Rayleigh Wave Tomography of Ningxia and Its Adjacent Areas Based on Ambient Noise
Xie Hui,Ma Heqing,Ma Xiaojun,Li Qingmei,Zhang Nan,Ren Jiaqi
Abstract:
In this article, the vertical components of the continuous waveform data of 90 seismic stations in Ningxia and its adjacent regions recorded from January 2012 to December 2013 are used to obtain the Rayleigh surface wave group velocity dispersion images in the study area (101°-112°E, 31°-42°N) according to the method of noise imaging, with period between 6s-50s and resolution of 0.5°. The Yinchuan basin in the 6s-26s period obviously shows a low velocity anomaly, which is not uniform and has a tendency to gradually weaken; the Guanzhong Basin in 6s-22s shows a strip of low velocity anomaly and demonstrates a transverse inhomogeneity, where velocity in the southeast is slightly faster than that in the northwest. In the 30s-50s period it shows that in the Yinchuan graben basin and its southern area, there is a large low velocity anomaly area, which moves from northeast to southwest. It shows that between the main active tectonic zones, like mountains and basins, there are obvious geomorphologic boundaries. For example, the deep fault near Liupan Mountain is the dividing line between two large tectonic units of eastern and western of China. The inversion results have good correlation with the geological structure and the stratigraphic landform. The results are consistent with the results of artificial seismic section tomography across the basin. It provides an important basis for the dynamics of active tectonic zones and the mechanism of earthquake occurrence in this area.
Key words:  Surface wave tomography  Crust and upper mantle  Background noise  Ningxia and its adjacent areas