Shown below is a table listing some of the advantages and disadvantages to both active and passive surveys. In reading these, please note that the terms passive and active cover a wide range of geophysical survey methods. Thus, the listed advantages and disadvantages are by necessity generalized and might not apply to any given specific survey.
Active | Passive | ||
---|---|---|---|
Advantage | Disadvantage | Advantage | Disadvantage |
Better control of noise sources through control of injected signal. | Because both sources and receivers are under the surveyor's control, he must supply both. Therefore, field equipment tends to be more complex. | Surveyor need only record a naturally occurring field; therefore, he need supply only a sensor and a data recorder. | Less control of noise because source of the signal is out of the control of the surveyor. |
Because propagating fields are generally measured, active experiments usually provide better depth control over source of anomalous signal. | Field operations and logistics are generally more complex and time consuming than passive experiments. | Field operations are generally very time efficient. Thus, passive experiments can be run over wider areas in a more cost-effective manner. | Because passive fields are generally the result of integrating anomalous geologic contributions over wide areas, identification of the source of an anomalous reading can be difficult. |
Many different source/receiver configurations can be used allowing for a wide variety of survey designs. This allows survey designers great flexibility in customizing surveys for particular problems. | Many different source/receiver configurations can be used allowing for a wide variety of survey designs. The increase in the number of field options inevitably leads to greater survey design costs and potentially to increased probability of field mishaps. | One or two well-established field procedures are generally used. Contractors can provide these surveys on short notice with relatively easily quantifiable results. | One or two well-established field procedures is generally used. This limits the amount of customization that can be done for specific problems. |
Once set up, active experiments are capable of producing vast quantities of data that can be used to interpret subtle details of the earth's subsurface. | The large quantity of data obtained in many active experiments can become overwhelming to process and interpret. | Interpretation of the limited set of observations can be accomplished with modest computational requirements quickly and efficiently. | The data sets collected in passive experiments are smaller than those collected in active experiments and usually do not allow for as detailed an interpretation. |