GBG Australia undertook a geophysical investigation to map the depth to bedrock for planning and construction purposes in two sites in the Iwate Prefecture, located on the main island of Japan. For this investigation seismic refraction was utilised to gain information on the depth of bedrock in addition to velocity information for each layer observed.
Seismic refraction data was collected using the Gemetrics Geode seismic recorder. An array length of 24 channels was utilised for most of the survey. A sledgehammer striking a metal plate was used to generate the seismic energy.
All geophone and shot locations were taken using a high accuracy DGPS and levels along the lines were taken using a laser level.