Landslide Periodicity and Prediction of Potential Landslide Sites

暖、腐殖气候条件下，浅层滑坡在同一坡址反复发生，是森林流域边坡发育的主要因素。在这种类型的滑坡中，滑坡在同一坡位的重复发生需要形成表土作为滑动材料。研究的目的是明确滑坡周期性的机理，并根据滑坡周期性预测浅层滑坡的潜在发生地点。结果总结如下：1。在日本鹿儿岛县鹿儿岛市和石碧山两个研究区域的陡坡上，分别形成了许多由火山碎屑流沉积和分解花岗岩组成的较新的和较古老的滑坡疤痕。鹿儿岛研究区和石璧山研究区同一坡址滑坡的复发周期分别在80 ~ 100年和200年以上。随着时间的推移，随着植物的入侵，表层土壤在滑坡疤痕上发生了改造。在火山碎屑流堆积区，表土的形成主要是由于滑坡后不到100年的物理和机械过程。而表土的形成既受花岗岩分解区化学作用的影响，也受物理力学作用的影响。根据滑坡的周期性规律，对表土较深的老滑坡疤潜在滑坡点进行了预测。表层土与坡面植被密切相关，因此可以利用植被作为指标来预测滑坡潜在地点。

Shallow landslide repeatedly occurs at a same slope site as a principal factor of slope development in forested drainage basins under warm and humic climate. in this type of landslide, recurrence of the landslide at the same slope site requires formation of the topsoil as sliding materials.The subjects of the study are to make clear the mechanism of landslide periodicity and to predict the potential sites for the shallow landslide based on the landslide periodicity.The results are summarized as follows;1. Many newer and older landslide scars have formed on steep slopes of two research areas, kagoshima-shi and shibisan, kagoshima prefecture, japan, composed of pyroclastic flow deposits and decomposed granite, respectively. The recurrence intervals of landslide at the same slope site are more than 80-100 years at the kagoshima-shi research area and more than 200 years in the shibisan research area, respectively.2. The topsoil has reformed on the landslide scars with lapse of time associated with invasion of plants. The formation of topsoil is mainly due to physical and mechanical processes during a period of less than 100 years after landsliding at the pyroclastic flow deposits area. While the formatiom of topsoil is due to chemical processes as well as the physical and mechanical processes at the decomposed granite area. The potential landslide sites which are old landslide scars with deep topsoil are predicted based on the landslide periodicity. The topsoil is closely related the vegetation on the scars, therefore the potential landslide sites can be predicted by using of the vegetation as an index.