Seismic Recording Systems

Multi-channel seismic recording systems are widely available from a number of different manufacturers. Photos of two examples of systems currently available and commonly used for near-surface seismic exploration are shown below.

Geometrics StrataView	OYO Geospace DAS 1

Geophones are connected to the recording system by electrical cable. Each cable is capable of carrying the signals produced by several (10s to 100s) of geophones at once, rather than having a single cable go to each geophone separately. An example of a set of geophones connected to seismic cable is shown to the right. This particular cable was commonly used for deep exploration, such as was done in the oil and gas industries during the 1970s through the 1980s*. If you look carefully, you might notice that along the cable there are orange strips. These strips are actually plastic connectors into which the geophones connect. In this case, the orange connectors (called take-outs) are spaced every 110 feet along the cable. For near-surface exploration work, this spacing can be reduced to as little as 5 feet.

Most modern recording systems can display the ground motion recorded by each geophone almost immediately after recording it. Ground motion is stored either directly to digital recording tape or to a computer hard disk in the recording system itself. The recording systems typically used in near-surface exploration are capable of recording ground motion from between 24 and 142 geophones. As a rule of thumb, these recording systems usually cost about $1000 per recording channel. Thus, a system capable of recording ground motion from 48 geophones at once will cost somewhere in the neighborhood of $48,000.

*The oil and gas industries still do a significant amount of seismic exploration but just not with the systems illustrated here. Most modern seismic exploration is based on the collection of data over a three-dimensional grid. This requires large numbers, thousands, of geophones on the ground and recording systems capable of recording ground motion from as many sites. The technologies used to do this are significantly different from those described here, although the basic principles are exactly the same.

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