Abstract: Heat reservoir temperature of water samples collected from 14 hot springs on the northern segment of the Honghe fault zone is calculated by using SiO₂-geothermometer, and in connection with local geothermal gradients, circulation depth of the hot spring waters is also calculated. Meanwhile, frequency and focal depth of earthquakes occurring from 886 to 1987 are counted up and analysed. From the point of view of weakening effect of water on fault and its wall rocks, the author discusses the effect of deep circulation of the hot spring water on strength and frictional force of fault and seismic activity. The result indicates that difference in the seismic activity on each sub-segment is related to the degree of weakening effect of water on the various sub-segments. It is suggested that the Eryuan sub-segment on which the circulation depth of the hot spring waters is greatest corresponds to a slip zone, while the Jianchuan and Midu sub-segments on which the circulation depth of the hot spring waters is smaller, and Dali sub-segment with very few hot spring correspond to the locked zones, and that a strong earthquake would be prepared at both ends of the zone in which circulation depth of hot spring waters is greater.

Key words: The Honghe fault zone, SiO₂-geothermometer, Heat reservoir temperature, Circulation depth, Seismic activity, Weakening degree

摘要： 利用SiO₂地热温标计算了红河断裂带北段14个温泉水的热储温度,并结合当地地温梯度计算了温泉水的循环深度,同时统计分析了886～1987年间的地震频度和震源深度。作者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断裂强度、断裂摩擦力和地震活动性的影响。结果表明,各亚段地震活动性差异与水对各亚段的弱化程度有关。认为温泉水循环深度最深的洱源亚段相当于"滑移区",而温泉水循环深度较浅的剑川亚段和弥渡亚段及温泉稀少的大理亚段则相当于"闭锁区",强震将孕育于温泉水循环深度较深的地区的两端。

关键词: 红河断裂带, SiO₂地热温标, 热储温度, 循环深度, 地震活动性, 弱化程度