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MS8.0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...