The reflected waves return to the surface and can be detected by small instruments called geophones which are sensitive to vibration. Instruments attached to geophones will record the moment that the source generated the sound and the moment that a reflection was sensed by the geophone. Reflection seismic acquisition requires equipment for generating sound of the right type and intensity, geophones, cables to connect geophones to recording devices and computers to convert the raw data into a format that can be used to map the earth's crust from the information. The field trip On Friday evening we made the five hour drive to south-central Colorado, meeting a snow storm as me approached our destination on the west side of the San Luis Valley, Colorado. The San Luis Valley is nearly surrounded by mountains with several peaks exceeding 12,000 feet.
Cool air flows down the mountains into the valley and has no way to escape.
In spite of the cold, we met in the operations room for some hot coffee, a safety briefing, and an overview of the project. The area of investigation included both level valley floor and rolling foothills. Today we were to witness acquisition of a very small and level portion of the total area of the project. Soon we were off to the staging area and acquisition site to view the equipment. The seismic source Mechanical vibrator trucks were used for most of the survey, although small dynamite charges in shallow bore holes were required where the terrain was too soft for the heavy trucks.