An empirical study of sediment disasters subsequent to earthquake damages

本研究分为1999年台湾集集大地震后的后续泥沙灾害研究及地震后三重县藤原镇的泥石流研究两部分.在台湾的研究a）。地震后边坡破坏的地貌变化为了解集集地震后边坡破坏的性质与形态的变化，我们在两个典型的破坏区进行了现场基础研究。在竹粉二山地区，发现滑坡坝的溢洪道被冲刷，河中的一些淤地坝也受到严重破坏。以草岭地区为例，说明集集地震造成的崖顶落差20公尺。为了弄清地震后地基性质的退化情况，我们继续进行了现场地震勘探。地震后的台风影响台湾在2004年夏季的台风影响后，1999年集集地震造成的山坡地泥沙灾害扩大到受灾区的北方地区。在大甲溪中游进行调查，发现灾害扩展的典型模式是先发生泥石流，再由支流泥沙补给干流，然后河床抬高，最后发生洪水灾害.三重县藤原町的泥石流研究地震后藤原町发生了几次泥石流，但因果关系尚不清楚。通过实地调查，阐明了上游补给的河床泥沙回流和河岸侵蚀是藤原镇泥石流复发的主要因素。此外，我们发现，泥石流的复发可以预测使用10分钟的降雨量数据。

This study consists of two parts that the research for subsequent sediment disasters after the Chi-chi earthquake in Taiwan 1999, and the research for the debris flows in Fujiwara town in Mie prefecture subsequent to an earthquake.1. Research in Taiwana). Geomorphological change in slope failures after earthquakeTo clarify the change of property and form of the slope failure induced by the Chi-chi earthquake, we conduct the basic on site research in two typical damaged areas. In Chu-fen-erh-shan area, we found the spillway from the landslide dam was eroded and some check dams in the stream damaged seriously. In Tsaoling area, we illustrated the 20-meter fallback at the cliff top, which made by the Chi-chi earthquake. And we continued the seismic exploration on site in order to clarify the degradation of ground property after earthquake.b). Typhoon impact after the earthquakeAfter the typhoon impact in the summer of 2004 in Taiwan, sediment disasters on mountainous slope expanded to the northern area of the damaged area by Chi-chi earthquake in 1999. We surveyed in the middle stream of Tachiachi river, and found the typical pattern of a disaster expansion that a debris flow occurs first, after that the main stream is fed by the sediment from tributaries, then the riverbed raises, the flood disaster occurs at last.2. Debris flows research in Fujiwara town in Mie prefectureSeveral debris flows occurred in Fujiwara town subsequent to an earthquake but the causal relationship is not clear. We clarified the main factor for recurrences of debris flows in Fujiwara town were the resumed flow of the sediment in riverbed supplied from upstream and eroded riverbank through the field research. Also, we found that a recurrence of debris flows can be predictable using 10 minutes rainfall data.