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地质和地球物理资料表明在上、中、下地壳内各有力学上的软弱带(σ_1-σ_3<10MPa),这从实验测定的岩石稳态流动性质得到证实。软弱带出现的深度主要取决于岩石类型和大地构造区,估计在10～15km、20～28km、25～40km范围。此外,地壳中广泛分布的延性、半脆性断层带也说明轶弱带可以出现在地壳10km以下的任何地方。目前虽然还没有下地壳代表性岩石的实验资料,但是力学性质相近的岩石实验结果支持这种假设,即莫霍面是力学上的不连续面,其下部是强度更高的橄榄岩。这种不连续性程度与温度和应变速率有很大关系。
Geological and geophysical data indicate mechanistic weaknesses (σ_1-σ_3 <10 MPa) in the upper, middle and lower crust, as evidenced by the experimentally determined steady-state flow properties of rocks. The depth of the weak zone mainly depends on the type of rock and tectonic zone, estimated at 10-15 km, 20-28 km and 25-40 km. In addition, the widely distributed ductile and semi-brittle fault zones in the crust also show that weak zones can occur anywhere below 10 km crust. Although experimental data on representative rocks from the lower crust are not yet available, experimental results of rocks with similar mechanical properties support the hypothesis that the Moho is a mechanical discontinuity and the lower part is a higher-intensity peridotite. This degree of discontinuity is strongly related to temperature and strain rate.