Compared to the equipment used for gravity and magnetic and even resistivity surveying, the amount and complexity of the equipment used in seismic surveying can be staggering. Due to the complexity of the equipment (which stems from the complexity of the field surveys we would like to employ), seismic surveying can become logistically very intensive.

Typical seismic acquisition systems consist of the following components.

• Seismic Source - This is nothing more than an apparatus for delivering seismic energy into the ground. Sources can vary greatly in their size and complexity. All, however, share the following characteristics:

• They must be repeatable. That is, the nature of the energy delivered into the ground (its amount and the time duration over which it is delivered) should not change as the source is used in different locations and

• Time of delivery must be controllable. We must be able to tell exactly when the source delivered its energy into the ground. In some cases, we can control the time of delivery. In others, we simply note the time the source delivered its energy.

• Geophones - These are devices capable of measuring ground motion generated by the seismic source. As we will describe later, these typically convert the ground motion into electrical signals (voltages) that are recorded by a separate device.

• Recording System - This actually consists of a number of components. In essence, this entire system does nothing more than store the ground motion detected by a number of geophones. This number could be quite large. Today, it is not unusual for oil exploration surveys to record ground motion detected by 1000's of seismometers at a time. In addition to recording ground motion, this system must also control the synchronization of the source. It consists of not only a "black box" to store information but also numerous electrical connections to the geophones and the source and usually a device to select subsets of the installed geophones to record.