秦岭北缘断裂带温泉水循环深度与地震活动性的关系研究

研究了秦岭北缘断裂带温泉水的氢氧同位素和氦同位素,同时通过温泉水的热储温度和当地地温梯度计算了温泉水的循环深度;统计分析了1900-1997年间的地震频度.从水对断裂及其围岩的弱化的角度讨论了温泉水深循环对地震活动性的影响.结果表明各段地震活动性的差异与温泉水循环深度的差异有关.认为循环深度较深的陕西段孕育强震的可能性较小,而循环深度较浅的青海段和甘肃段是孕育强震的危险区,其中甘肃段可能是强震的最危险区.

Research on the Relation of Circulation Depth of Hot Spring Water with Seismicity in the Northern Margin Fault Zone of Qinling

The hydrogen and oxygen stable isotopic composition and the helium isotopic composition of the hot spring water in the Northern Margin Fault Zone of Qinling are studied. Making use of heat reservoir temperature, and in connection with the local geothermal gradients, circulation depth of the hot spring waters is calculated. Meanwhile frequency of earthquakes occurring from 1900 to 1997 is counted up and analyzed. Form the point of view of weakening effect of water on fault and its wall rocks, the effect of deep circulation of the hot spring water on seismic activity is discussed. The result indicates that difference of seismic activity among each segment is related to difference of the circulation depth of hot spring water in each segment. It is suggested that a risk of strong earthquake is less possible on the Shanxi segment in which the depth is greater, but are more possible on the Gansu segment and the Qinghai segment in which the depth is smaller, and it is most possible on the Gansu segment.