摘要
采用作者最近新提出的频谱参数化方法,对北京电信传输台网2447个远震P波到时残差数据进行了反演,说明新的参数化方法能有效地应用于实际数据.反演结果表明,京津唐张地区深部100多km内存在明显的速度横向不均匀性;50 km以上部分的结构与地表的地质构造有较好的对应关系:在燕山隆起区下部表现为高速异常区,而凹陷区下部则呈现低速异常区;深度100 km以下,地表构造的痕迹逐步消失,异常蝠度也相应降低.研究区域范围内存在三个大的低速异常块体,其中以天津、唐山附近的水平尺度为100 km左右的低速异常区幅度最大,向下一直延伸到约100 km的深度,而且在100 km以下存在一低速异常构造与之对应.研究区域内发生的强震大部分都位于低速异常区边缘向高速区过渡的梯度带上.
An inversion study of 2447 teleseismic P-wave travel time residuals observed at Beijing network is given in this paper, using the spatial frequency domain expansion parameterization method proposed recently by the writers. It is proved that the new method can be effectively applied to real data. The results show that there are obvious lateral heterogeneities deep to 100 km beneath the area. The velocity anomaly images in the upper 50 km show certain correlation with the shallow geological features: high velocity zone beneath uplift areas and low velocity zone beneath depressional areas. Below the depth of 100 km, this correlation disappears gradually and the amplitudes of the anomalies decrease. Three prominent low velocity anomalies have been found within the studying area. Among them, the Tianjin-Tangshan anomaly has maximum amplitude. It extends about 100 km in horizontal direction and continues down to a depth of nearly 100 km. Below it, there is another low velocity anomaly. Almost all the strong earthquakes occurred within this area are situated in the transition zone between these high and low velocity anomalies.
出处
《地球物理学报》
SCIE
EI
CAS
CSCD
北大核心
1990年第3期267-277,共11页
Chinese Journal of Geophysics
基金
地震科学联合基金
关键词
地壳
上地幔
P波
速度结构
Inversion, Beijing network area, Three dimensional velocity, Lateral inhomogeity.
