Controlled-source

Referring to geophysical or scientific investigations where the energy or signal utilized for probing the subsurface or other physical environment is artificially generated and precisely regulated. This contrasts with investigations relying on naturally occurring energy sources, such as earthquakes (in seismology) or natural radiation. Key aspects include the known location, timing, and characteristics (e.g., frequency, amplitude) of the signal, allowing for controlled experimentation and data interpretation. controlled-source methods are crucial for detailed imaging and property estimation, providing insights impossible or difficult to achieve using passive observation. The precise control allows for quantifiable and repeatable experiments, leading to more definitive conclusions about the probed system.

Controlled-source meaning with examples

• Seismic surveys using controlled-source methods involve generating sound waves, often with explosives or vibroseis trucks, and recording the reflections to map subsurface geology. This technique offers high resolution and precise data control, ideal for oil and gas exploration or geological hazard assessment. Careful design and execution of the energy source are essential to ensure consistent signal penetration and avoid unwanted noise, ensuring good data quality.
• In electromagnetic (EM) geophysics, controlled-source EM (CSEM) techniques use a transmitter to generate an electromagnetic field, and receivers to measure the response of the subsurface. This is commonly used for marine resource exploration and understanding the earth's electrical conductivity. This allows for exploration even in very deep water where it can take weeks to survey a relatively small area.
• Controlled-source methods can also be applied to other scientific disciplines. For instance, in materials science, the controlled application of heat or radiation can be used to observe and characterize material behavior under stress. Similarly, in environmental science, controlled releases of tracers can be used to study fluid flow or pollutant transport in ground water.
• Unlike methods which rely on natural earthquakes to image the subsurface, controlled-source methods are specifically designed and engineered to emit an excitation or signal to provide precise data. In this case, it might be through a vibrator to produce seismic waves to provide high resolution data about the earth's geology to determine geological composition and structure.