从地震前兆差异性看地下流体突变型前兆的物理本质

DISCUSSING THE PHYSICAL ESSENCE OF BURST-TYPE UNDERGROUND FLUID PRECURSOR THROUGH EARTHQUAKE PRECURSOR DIFFERENCE

利用地下流体前兆资料．从前兆异常的差异性出发．研究了突变型前兆的形成条件和影响因素，结果表明：突变型前兆集中出现在化学参数中，而在地下流体物理参数中出现较少，仅在富含天然气的油井水位中出现；出现突变型前兆的井（泉）具有含水层埋藏深、地下水循环路径长、温度高的特点。这一结果表明，地下流体突变型前兆的形成与观测井（泉）的水文地质条件、水文地球化学环境以及观测参数的物理化学性质有关。其形成不是一个单纯的物理过程，本质可能是震源应力场或区域构造力的变动导致发生的一种物理化学变化过程，含水层卸载是形成突变型前兆的主要力学原因。基于此种认识，给出了地下流体突变型异常的物理过程，并对其力学因素和物质来源进行了分析和讨论。

Proceed from the difference of fluid precursor,the conditions to form abrupt precursorand the factors to influence them are studied by using underground fluid precursor data. Theresult shows that the abrupt precursor mainly appears in chemical observation parameters,while in physical observation parameters, it is only observed in the water levels of the oilwells that have rich natural gas,and that the wells (springs)that show abrupt precursorshave the features of deeply -buried aquifer,long cycle path of grornd water and high tempera-ture. This indicates that the formation of abrupt underground fluid precursor is relative to thehydrogeologic condition and hydrogeochemical environment of observational wells (springs)as well as the physical,chemical character of observation parameters, Its formation isn't apure chemical procession,but a physical and chemical one caused by the change of focal stressfield or regional tectonic stress in essence. And thc unloading of aquifer is the main reason toform abrupt precursor. Based on this knowledge, the physical procession that the abrupt underground fluid precursor forms is given, and its mechanical factors and material source areanalyzed and discussed.