Final answer:
The best way to identify an active plate boundary is through the study of earthquake patterns, which is the most direct method and provides clear evidence of the locations and types of plate boundaries.
Step-by-step explanation:
The best way to identify an active plate boundary is through the study of earthquake patterns. Earthquake activity tends to be concentrated along plate boundaries, where the movement of Earth's tectonic plates leads to seismic events.
By mapping the locations of earthquakes, geologists can infer the positions and types of plate boundaries. Divergent boundaries, where plates pull apart, convergent boundaries, where one plate dives beneath another, and transform boundaries, where plates slide past each other, all produce different earthquake patterns that are distinctive and observable on seismic maps.
Volcanic activity also closely follows plate boundaries, especially at convergent and divergent boundaries. Analysis of faults and volcanic rocks can provide further evidence, but for immediate identification, the pattern of seismic activity is the most direct method.