福建沿海地区地壳S波速度结构和泊松比分布特征

THE S WAVE VELOCITY STRUCTURE AND POIS-SON' S RATIO DISTRIBUTION CHARACTERISTIC IN FUJIAN COASTAL AREA

本文根据福建沿海地区人工地震测深剖面的单分量地震记录,对S波信息进行开发研究。通过对地震记录重新采样,数字处理与分析,获得了该区地壳S波速度模型,结果发现:福建沿海地区的地壳与上地慢S波速度结构可分为三层,即上地壳,中地壳和下地壳;在中地壳普遍发育一层速度为3.4——3.5km/s的低速层,厚度约3—4km;MOHO面深度,泉州以北最浅,仅为28km,宁德以南最深,为32km。 结合P波速度模型,我们获得了该区地壳平均泊松(Poisson)比模型。漳州盆地和福州盆地平均泊松比值表现出异常高值,而泉州、渔溪地带的平均泊松比为相对低值,结果显示:泊松比值的大小与断裂交汇区,特别是地热异常区具有良好的对应关系。

Based on the D, S. S data obtained from Fujian coastal area, the S wave velocity model is gained by sampling analog tape recore, digital dealing and the analysis. The result shows that the S velocity struc-ture of the crustal in Fujian coastal area is composed of three layers, that is the upper-crust, mid-crust and lower-crust. In the mid-crust, there is a low velocity layer with 3-4 km thick andwith the velocity 3.4-3.6 km/s. The Moho deepth in Quinzhou area is in the most shallow, which is only 28 km, but that in Ningde is in the deepest, which is 32 km. Combined with P velocity model, the average poission's ratio of the crust in this area are obtained. The poission's ratio in zhangzhou and Fuzhou basins shows abnormally high value, however, whose in Quizhou and Yuxi area show relatively low value. The results indicate that the poisson's ratio has corresponding relations with the local faults area, especially with geothermal area.