A Land Streamer Aided, Three-Dimensional (3-D) Seismic Reflection Survey, Belt, Montana

The Three-Dimensional (3-D) seismic reflection method has not been extensively utilized for<br>shallow subsurface investigations because of the relatively high cost of performing 3-D surveys. We<br>have designed and constructed a system that makes 3-D seismic reflection an affordable option for<br>shallow subsurface exploration by significantly reducing time and manpower. In a fashion similar to<br>marine work, an All Terrain Vehicle (ATV) tows an array of four parallel seismic cables, or land<br>streamers. Each streamer consists of 24 gimbaled geophones. The ATV drags the array from station to<br>station and shots are taken while the array is stationary. We tested our system near Belt, Montana to<br>help locate abandoned subsurface coal mines. For this survey, our receiver, receiver line, source, and<br>source line spacings were all 1 m. In total, we covered a surface area of 100 m by 34 m and achieved a<br>nominal fold of 24. Typical combined advance and occupation times for each station were less than 30<br>seconds using a crew of three people. A brute stack shows horizontal layering of the local geology.