The site investigation costs may be very high since landslides may be extremely large, structurally complex and topographically severe, it is therefore advantageous in suitable circumstances to carry out geophysical surveys to define the structure and to guide optimum siting of boreholes and pits, and ultimately the installation of piezometers, inclinometers etc. Standard surface geophysical techniques including the seismic, electrical resistivity, acoustic emission and borehole methods have all been applied with varying success to look at a landslide before a major site investigation starts.