Common rock samples have been shown to have velocity orthotropy according to measured experimental results . the anisotropy of rock is cased mainly by three factors ( 1 ) aligned cracks . ( 2 ) the intrinsic anisotropy of mineral crystal as the results of crystallization 对岩石样品的测试发现，在普通岩石具有速度正交各向异性特性，既有定向排列的裂缝和岩石的结晶所致，也有层理与岩性特征(定向颗粒或孔隙)构成。
