【摘要】 2000年4月9日19时59分18.2秒,在西藏自治区波密县境内易贡乡发生了特大崩塌—滑坡—泥石流。构造上它发生在印度板块阿萨姆楔入角复合地带的西侧,也是高原腹地向东侧山地下降的过渡带,重力作用明显。根据便携式GPS定位仪实地测定和滑坡前后的卫星影像分析,崩塌—滑坡—泥石流堆积物形成了一座长约5.7km、宽约1.5km的“天然大坝”,完全堵塞了易贡藏布河干流,崩塌滑坡体总方量超过3.8×10~8m~3。根据区域地震台网的记录,其振动持续的时间为6min,其中最大振幅的持续时间为2min。震相分析表明有3组较为明显的震相,对应着3次较大的地表振动。计算获得崩塌滚落的平均速度约为48m/s,伴随崩塌滚落的同时,滑坡泥石流的平均滑动速度也达到了16 m/s,比一般泥石流流动速度要大一倍。更多还原

【Abstract】 At about 8 o’clock on April 9th 2000, a large rock fall - landslide occurred near Yi’ong, southeastern Tibet. Topographically, this region lies in a transitional zone from the highs of the Tibetan plateau to the lower mountain areas, where the gravity effect dominates the surface geological process. Tectonically, Yi’ong is located to the west of Assam where the India plate wedges into the Eurasia plate. Field investigation with the GPS 12XL combined with the analysis of satellite images taken before and after the landslide revealed that the deposits of the landslide formed a "dam" that is 5. 7 km long and 1. 5 km wide, which entirely blocked the Yi’ong River. The volume of the deposits is more than 3. 8X 10s m3. According to the recordings of the local seismic network, the landslide occurred at 19:59:18. 2 local time and the duration of the vibration is about 6 minutes. Three seismic phases were identified from the seismogram, which represent three large surface vibrations. The speed of the debris flow is about 48 m/s and that of the mud flow is about 16 m/s, which is much larger than a normal mudflow.更多还原