Abstract

The characteristics of the triggered earthquake activity of the Đà River ladder of hydropower plants have been carrying out in this study. The results have shown that: The reservoir triggered earthquakes occurrence in the places of strong metamorphosed rocks (gneiss, marble...), granitites and thick limestone that have been strongly broken and with the value of the Vp/Vs ratio equal to 1.63-1.67. In the case of Đà River ladder of hydropower plants, the reservoir triggered earthquakes occurrence needs the additional condition that the height of the reservoir water level is more than 100 m; The danger of the triggered earthquake occurrence must be occurring in the following places: The segment of the Mường La - Bắc Yên seismic source connected with the Sơn I La reservoir, from lowland of the Huội Quảng dam to the lowland of Son La dam. The maximum of the triggered earthquake magnitude, Mmax.kt = 5.0-5.1; The segment I from The Pa Uon bridge to the Son La dam of the Đà River seismic source has the I dangerous of triggered earthquake with the maximum of the magnitude, Mmax.kt = 5.4- I 5.7; Almost the whole of Mường Tè seismic source and a segment of the Mường Nhé I source that connected with the Lai Châu reservoir have the dangerof triggered earthquake with the maximum magnitude, Mmax.kt = 4.8-5.1.