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After compiling all the previous data from the area it is our job to fill in the gaps in information. Subsurface information is obtained using geophysical/seismic techniques. Eighty test sites were surveyed across the region, in areas where well logs or other sources of data were not available.
At each test site data were acquired with an array of 24 geophones at 5 m spacing. The source was an in-hole shotgun-shell. Here is a shot going off.
The data collected on this survey were analyzed using:
- Refraction analyses to estimate near-surface velocity structure, and hence depth to bedrock or layering (at sites less than 30 m depth).
- Seismic reflection analyses at sites where surficial sediments exceed 50 m in thickness. Reflections are generated at stratal contacts. A low-fold common midpoint seismic section is generated from the deep sites.
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