Final answer:
A fault line is the correct term for a fracturous zone in the Earth's crust where laser-ranging devices can detect movements. Fault zones define where tectonic plates slip past each other, and seismic surveys help in studying these movements. The detection of fault lines is critical for assessing earthquake risks.
Step-by-step explanation:
The word that best fits the definition given is a. Fault line. Laser-ranging devices are capable of detecting minuscule movements of the Earth's crust along a fault line. Fault lines are fractures or discontinuities in the Earth's crust, along which there has been movement of the blocks of the crust on either side of the fracture. They can be the sites of significant seismic activity such as earthquakes, which occurs when the stress accumulated in the crust is released.
Fault zones are areas where cracks or faults in the Earth's crust are present, allowing the tectonic plates to move and slip past one another. This movement can be tracked using various geological and technological methods, including the use of laser-ranging devices and seismic surveys. These tools provide valuable data for predicting seismic hazards and understanding the geological dynamics of our planet.
For example, in seismic surveys, sound waves are sent into the Earth and the waves reflected back to the surface are recorded to create an image of the subsurface, which helps geologists to detect the presence of fault lines. The study of how these plates move, particularly along fault zones and plate boundaries, is also important for the assessment of earthquake risks and the potential for future seismic events.