青海玉树M_S 7.1地震震后断层流体地球化学连续观测

Continuously observation of fault fluid geochemistry after Yushu M_S 7.1 earthquake

为了探究地震对断层流体逸出的影响和震后流体地球化学特征随时间的变化与余震对应关系,在玉树地震断层进行了震后断层土壤气氡、CO2以及泉水气氡等流体地球化学连续观测.观测结果发现震后一个月的时间内CO2和土壤气氡、水氡浓度都保持在比较高的水平.此后浓度有一个先下降在上升的变化过程,在浓度下降变化的过程中,余震比较少;而在浓度上升过程中,余震活动比较活跃,数量多,震级大.玉树地震后断层带CO2和壤气氡、水氡浓度增加,表明地震前后断层的活动性增强,改变了区域内原有的应力场水平,导致了深部流体沿着地震断裂运移到地壳浅部.

For understanding the effect of earthquake on fault fluid escaping and relationship of post-seismic fault fluid geochemistry and aftershock activities, continuously fault gas geochemical observations were carried to investigate changes of soil CO2, Rn and spring Rn at earthquake fault after Yushu Ms 7.1 earthquake. The observed results show concentration of soil CO2, Rn and spring Rn kept in high level in one month after the Yushu earthquake happened. Subsequently the concentrations firstly decreased and then increased. Aftershock little happened during the fault gas concentration decreasing stagel however during the fault gas concentration increasing, strong aftershock happened and aftershock magnitude and quantities are large. Increasing of concentration of soil CO2, Rn and spring Rn at Yushu earthquake fault after the earthquake indicate that fault activity increased before and after earthquake. Earthquake changed regional stress conditions and made deep fluid escaping to crust surface along earthquake fault.