京津唐地区震源深度分布初探
A PRELIMINARY STUDY OF FOCAL DEPTH DISTRIBUTION IN THE BEIJING-TIANJIN-TANGSHAN AREA
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摘要: 在对唐山—张家口一线地震进行定位时,采用台偶时差法测定震中,不同震相之间到时差求震源深度的方法,提高了定位的精度.本地区的震源分布在5—22km的深度范围,这和估算的地壳岩石强度随深度的分布相吻合.从而推断,这里的地壳具有上部脆性、下部塑性的特性,其过渡带的深度约20km.Abstract: When locating the earthquakes along the line Tangshan to Zhangjiakou in the Beijing-Tianjin-Tangshan area,we select the differences of arrival times at station-pairs to determine the position of the epicenter and use the differences in arrival times of seismic phases to determine depths of foci,seperately. This can raise the location accuracy. The earthquake sources of this area distribute between the depths of 5—22 km. This is in agreement with the estimated distribution,with depth,of crustal rock strength. So,we deduce that the crust here has the following characterisic: the upper part is fragile,and the lower part is plastic. The transition depth is about 20 km.
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