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

首先，1995年兵库县南部地震引发了六歌山脉的许多斜坡坍塌。尝试从地震记录中找出与斜坡失稳分布相对应的频率特征。1)推定最大加速度约为300-400 Gal，主频小于或等于1赫兹。2)余震的分布与崩塌的分布有很好的一致性。因此，断裂能在断裂面上的分布有可能反映在斜坡上。第二次1997年鹿儿岛-北部省地震在其所在地区引发了多次斜坡崩塌。1)与沉积岩相比，花岗岩下伏的山坡更易发生崩塌。2)花岗岩覆盖区崩塌密度为30.2个/1km2，沉积岩覆盖区为7.6个/km2。在花岗岩覆盖区，坡体崩塌密度随海拔高度和坡角的增大而增大，但坡体崩塌多发生在海拔较低的缓坡地带。从大量的相关文献中收集了1900年后日本发生的24次斜坡运动的数据，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.