Synthetic study on the hillside disaster and stability of woods-land resulting from Earthquakes

1995年兵库县南部地震引发的六高山第一次多起边坡崩塌。试图从地震记录中提取与斜坡破坏分布相对应的频率特征。1)据推测，最大加速度约为300-400 gal，其优势频率为1 Hz或更低。2）余震的分布与斜坡崩塌的分布有很好的对应关系。因此，断裂面上的破裂能分布可能反映了斜坡崩塌的破裂能分布。其次，1997年鹿儿岛县北生府地震引发了该地区多起斜坡崩塌。1)与沉积岩相比，花岗岩下的山坡更容易发生崩塌。2)花岗岩和沉积岩下的崩塌密度分别为30.2和7.6。坡体密度随海拔高度和坡角的增加而增加，但在花岗岩下伏地区，坡体破坏多发生在海拔较低的地区和平缓的斜坡上。第三，研究目的是加深对地震泥石流形态和地质特征的认识。从大量的相关文献中收集了1900年以后发生在日本的24次斜坡运动的资料，并进行了调查。

First many slope collapses in the Rokko Mountains triggered by the 1995 Hyogo-ken Nanbu Earthquake. The correspondence to the distribution of the slope failurcs was tried to set frequency characteristics from the seismograms. 1) It is presumed that the maximum acceleration was about 300-400 gal and its predominant frequency was 1 Hz or less. 2) The distribution of the aftershocks corresponds well with that of the slope collapses. Therefore, it is possible that the distribution of breaking energy on the fault plane is reflected that of the slopecollapses.Second the Kagoshima-ken Hokuseibu Earthquakes 1997 triggered many slope collapses in it's area. 1) The hillslopes underlain by granitic rocks are largely susceptible to slope collapses in comparison with those of sedimentary rocks. 2) The density of slope collapses, number of slope failures per 1km2, is 30.2 in the area underlain by granitic rocks and 7.6 in the area underlain by sedimentary rocks. The density of slope collapsesincreases with the height above sea level and the angle of slopes, In the area underlain by granitic rocks, however, many slope failures occurred at the lower height area and gentle slopes.Third the purpose of the study is to improve the understanding of morphological and geological features of debris flows caused by earthquakes. Data of 24 slope movements which occurred in Japan after 1900 were collected from number of related literatures and investigated.