SUMMARY

The initial results of the induce earthquake study in Sông Tranh 2 reservoir

Cao Đình Triều, Đinh Quốc Văn, Bùi Anh Nam, Hà Vĩnh Long

In the framework of this paper the authors have carried out the study of the Induce Earthquake Occurrence in the last time in Sông Tranh 2 reservoir. The obtained results have shown that:

1/ The earthquakes occurred in the last time located in the Sông Tranh 2 reservoir are the induce earthquake ones. The earthquake epicenters distributed along the Trà My - Trà Bồng sub-latitudinal fault zone (280⁰-300⁰). The maximum earthquake could be occurs in the reservoir probably reach to magnitude 5.7 to 6.1. The coefficient b of the Gutenberg - Richter law has the value b= 0.8317, more than b of the natural earthquake of the Sông Tranh 2 region (b= 0,604). The frequency of the earthquake occurrence with the magnitude from 4.5 to 6.0 is the following: M= 4.5 is 11 months; M= 5.0 (29 months); M= 5.5 (76 months); and M= 6.0 (198 months).

2/ The earthquake occurred at 13 hour 41 minute 28 second (GMT), M_S= 4.6, I₀= 6.0 (MSK-64), 22 October, 2012 has the epicenter located at the center of the reservoir, 5.5 km far from the dam in the west. The focus mechanism: depth of the hypocenter is about 4.5 km; the length of the fault plane is 1.8 km with the direction 285⁰, normal right strike slip; dip angle 75⁰; direction of the stress field is 320⁰.

Người biên tập: TSKH Lê Duy Bách.