QUASI-STATIC CRUSTAL DEFORMATIONS DUE TO A SURFACE LOAD
QUASI-STATIC CRUSTAL DEFORMATIONS DUE TO A SURFACE LOAD
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表面载荷引起的准静态地壳变形
DOI：
10.4294/jpe1952.30.469
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发表时间：
1982
期刊：
影响因子：
--
通讯作者：
M. Matsu'ura
中科院分区：
文献类型：
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作者：
T. Iwasaki;M. Matsu'ura
本文讨论了复合介质表面受轴对称载荷作用下的准静态位移场，该复合介质由覆盖在分层粘弹半空间上的弹性层组成。应用线性粘弹性的对应原理，从相应的弹性问题中得到表面位移的积分表达式。本文通过一个由弹性表层、低粘度夹层和高粘度粘弹性底层组成的三层模型的数值算例，从多个方面考察了粘弹性位移的一般特征。（盆岭区），探讨了地壳上地幔流变结构的区域差异。Fennoscandia的隆升数据可以用一个三层模型很好地解释，该模型由100 km厚的弹性表层（岩石圈）和100- 200 km厚的低粘度层（软流圈）组成，后者覆盖在相对高粘度（1.4× 10 ~（22）泊）的底层上。软流层的粘度估计为1.4× 10 ~（20）-1.4 × 10 ~（21）泊。在邦纳维尔湖的例子中，岩石圈厚度为30- 40 km，软流圈粘度小于1.0-2.0× 10 ~（21）泊，可以充分解释隆升数据。从目前的分析来看，软流层的下限是模糊的。这些结果表明，两个构造不同的地区岩石圈厚度存在显著差异，但软流层粘度差异不大。
In this paper, we treat quasi-static displacement fields due to an axially symmetric load applied on the surface of a composite medium which consists of elastic layers overlying a stratified viscoelastic half-space. Integral representations of the surface displacements are obtained from those in the associated elastic problem by applying the correspondence principle of linear viscoelasticity. General features of the viscoelastic displacements are examined from various aspects through the computation of numerical examples for a three-layered model composed of an elastic surface layer, an intervening low viscosity layer and a viscoelastic substratum with relatively high viscosity.Uplift phenomena in two tectonically different regions, Fennoscandia and Lake Bonneville (the Basin and Range province), are analyzed to investigate regional difference in rheological structure of the earth's crust and upper mantle. The uplift data in Fennoscandia are well interpreted by a three-layered model which consists of a 100km thick elastic surface layer (lithosphere) and a 100-200km thick low viscosity layer (asthenosphere) overlying a relatively high viscous (1.4×1022 poise) substratum. The viscosity of the asthenosphere is estimated as 1.4×1020-1.4×1021 poise. In the case of Lake Bonneville, the uplift data are adequately explained by taking the thickness of the lithosphere as 30-40km and the viscosity of the asthenosphere as less than 1.0-2.0×1021 poise. The lower bound of the asthenosphere is obscure from the present analysis. These results show that there exists notable differences in the thickness of the lithosphere between two tectonically different regions, but not in the viscosity of the asthenosphere.