Abstract: The advanced geological hazards forecast study is necessary in the construction of a water tunnel NeelumJhelum (NJ) hydroelectricity project in Pakistan due to it complicated geological conditions. The Tunnel Seismic Tomography (TST) was used in the prediction since it has a better reliability and accuracy comparing with most of the existing forecast methods. Using the FK filtering function, the surface and side reflective waves could be filtered and separated. The reflective wave from the area to be excavated could be extracted. The function of the spatial observation and the velocity scan in the TST gives the precise analyzing of the velocity from the area to be excavated.  The inverse scattering migration image can enhance an accurate geological structure locating. The application results showed that the TST method using the migration image and the velocity structure can achieve a relatively accurate advanced geological hazard forecast, compared with the actual geological sketch, which can provide the reference for the field geological tectonic analysis and the surrounding rock mass classification.

Key words: Advanced Geological Hazard Forecast, The Tunnel Seismic Tomography (TST), Wave Fields Separation, Wave Velocity Scanning, Inverse Scattering Migration Image