根据强震形成的外核对流上升体对地壳的“顶托说”， 震后地壳要逐渐恢复到原态需经历一个被拉张的过程， 地温略微降低， 在大气圈中表现为干旱少雨。对1976-2008年中国西部36次震级Ms>6\^5级强震进行了分析， 发现强震之后在其下游同纬度500～2000 km区间每隔半年左右会出现干旱, 表明地壳的复原过程是一个振荡过程， 具有一定的规律性， 总体上时间间隔在6个月左右； 准半年振荡的维持时间与强震震级相关, 且随着震级的增强而变长， 对于6.5级地震的准半年振荡可维持2.5年， 对8级特强震可维持5年左右; 干旱中心集中出现的区域为84°E-94°E和105°E-115°E。

According to the theory of the outer core convection ascension body backwater on the curst of the formation of earthquake, the crust will gradually recover after the earthquake, the performance is that the crust will be stretched, the underground temperature will reduce, the precipitation will decrease. The analysis of the droughts after the earthquake whose Ms≥6.5 in western China from 1976 to 2008 shows that quasi-six months after the earthquake occurring, there will be a drought in downstream area range (500～2000 km) with the same latitude, indicating the the process of the crust recovery is a oscillation process with a certain regularity, there is a cycle of quasi-half-year. The appearing time of the quasi-half-year is closely related to magnitude, it′s vibration increase with the enhancement of magnitude, with last 2.5 years for Ms=6.5 earthquake and with last  5 years or so for Ms=8 earthquake. The two main areas of arid centers are 84°E-94°E and 105°E-115°E.