千葉県東方沖地震による松尾・成東・東金周辺地域の斜面崩壊 : 地震による洪積台地の斜面崩壊  [in Japanese] Slope failures caused by Chiba-ken-tohoh-oki-jishin along the edges of the Pleistocene upland, eastern parts of Chiba Prefecture : at Matsuo, Naruto and Togane area  [in Japanese]

Authors investigated the slope failures caused by Chiba-ken-tohoh-oki-jishin in the 17th of December, 1987. And we survyed the eastern parts of Shimofusa upland, Pleistocene. The number of slope failure sites is about more than 100. As the results of surveying each site, the each type of slope failures can be macroscopically grouped into the "earth fall group" and the "land slide group" and, however, microscopically classified into 5 types from A to E. The former group is composed of the types as earth avalanches falled down from the steep head scurps formed by the Kanto loam material and underlying Jyoso clay material or the consolidated sandy silt material, and also is approximately 80% of whole slope failures caused by the earthquake. The types of the latter group occurred at the reatively gentle slopes underlain by the fine-mediums and material of the Shimosa group and with the relvival-motion of old joints in it or the old slip surfaces. These studies are to protect against the slope failure calamities by future erthquakes due to the following two points. (1) counter protections aginst the types in the "eath fall group" (2) refuge facilities at the residence aginst the types in the "landslide group".