【摘要】 理解地貌过程以及认识过去灾害发生的频率,是自然灾害风险评价的重要任务。树木年轮由于其具有定年准确、连续性强、分辨率高和易于复本等特点,近年来被用到恢复过去灾害发生的时间。随着滑坡、泥石流等山地地质灾害性事件发生频率的增加,地质灾害风险管理和评价受到了越来越多的关注。在样品量足够的前提下,树木年轮方法可以精确地确定滑坡事件发生的年份。以甘肃南部武都区外纳乡的九房山滑坡为研究对象,利用树木年轮分析方法对该滑坡的灾害事件发生的时间进行了初步的研究。结果显示:1.树木年轮样品在1980—1982年,1984—1987年以及1991-1993年都出现了年轮宽度迅速减小或者迅速增加的现象。本研究将1980—1982年,1984—1987年以及1991—1993年定为滑坡活动年份,其中1992年和1993年的滑坡与当地记载的滑坡年份一致。强降水,地震影响以及不合理的灌溉活动都可能导致滑坡的复活,但降雨仍是导致九房山滑坡复活的重要因素。2.树木年轮样品中出现的偏心木和伪轮现象也是对滑坡灾害发生的佐证,说明受到滑坡灾害的影响,树木的生长环境发生了改变。更多还原

【Abstract】 The understanding of geomorphic processes and knowledge of past events are important elements for the assessment of natural hazards.With the frequencies of landslides,debris-flows and other geological disaster events increased in recent years,risk management and evaluation of geological disasters received more and more attention.Tree-ring data is widely used in the researches of disasters recovery of the past in recent years,which has the characteristics of accurate dating,strong continuity,high resolution and easy to copy.Tree-ring method can precisely determine the time of landslide happened using enough amounts of samples.The study area is Jiufangshan landslide,which is located in Wudu District of south of Gansu Province in Northwestern China.The Jiufangshan landslide reactivation periods are analyzed using tree-ring analysis method.The results show that:①There is an abrupt growth reduction or growth recovery in the year 1980—1982,1984—1987 and 1991—1993 in the tree-ring samples.So it was determined as landslide years in 1980—1982,1984—1987 and 1991—1993 in this study,in which the 1992 and 1993 landslides are in coincidence with the local archive data.Heavy precipitation,seismic impact and unreasonable irrigation activities may caused the landslide reactivation,while precipitation plays an important role in the landslide reactivation.②The eccentric wood and false rings appeared in the tree-ring samples are evidences of landslide events,these also indicate that the growth environment of trees is changed by the landslide activity.更多还原