Broadbent, M. 1973 Buller River power development: seismic refraction survey at Hawks Crag. [s.l.]: [s.n.]. Report / Geophysics Division 83 12 p.
Abstract: A seismic refraction survey was conducted in the Lower Buller Gorge near Hawks Crag, to determine the thickness of the gravels in the bottom of the gorge. Along each of two profiles across the Buller river, one being 150 metres downstream of Hawks Crag, the other being 300 metres upstream of the crag, the maximum thickness of the gravels encountered was 18 metres. Velocities of propagation of seismic compressional waves associated with the water-saturated gravels in the bed of the gorge were around 2.1 km/s. Velocities in the bedrock were 3.2 km/s in the upstream area and 3.9 km/s in the downstream area (auth.)