汶川8.0级地震前地下流体长趋势变化特征讨论

通过对汶川M_S8.0地震震中周围地区震前地下流体长期观测资料的分析表明, 震前地下流体出现了长趋势变化, 其特征是时间早、 范围广, 具有协调性以及向未来震中迁移等特征, 形态主要为趋势转折、 破年变、 加速等, 其中大多数为趋势转折变化。 进一步对比研究地壳形变、 地下流体长趋势变化发现, 地壳形变和地下流体长趋势变化迁移特征一致, 地壳形变长趋势时间较早于地下流体长趋势变化时间, 形变出现张压变化与水位变化有比较密切的关系, 即形变大部分出现缓慢压性变化或张性减缓变化, 水位大部分出现缓慢上升或下降减缓变化。 最后讨论了地下流体长趋势变化机理。

Discussion on the Long-time Trend Change Characteristics of Subsurface Fluid before the Wenchuan M_S8.0 Earthquake

Long-time observed data of Subsurface fluid from a wide circumferential region of the Wenchuan MS8.0 epicenter is analyzed before the earthquake.The result show that the subsurface fluids have long-time trend changes before the Wenchuan MS8.0 earthquake.The changes are characterized by earlier emerging time,wider range,compatibility and migration toward the epicenter etc.The shape of subsurface fluid long-time trend change is characterized by trend turn,annual variation damage and accelerating variation etc...