Final answer:
The relative velocity between two tectonic plates greatly affects the geologic activity at their boundary. Different types of plate boundaries and interactions can occur depending on the direction and speed of the plates' movement. This can lead to various geologic phenomena such as volcanic activity, earthquakes, and the formation of mountains.
Step-by-step explanation:
The relative velocity between two tectonic plates can greatly affect the geologic activity taking place at their boundary. Depending on the direction and speed of the plates' movement, different types of plate boundaries and interactions can occur. For example, when two plates are moving away from each other (divergent boundary), it can lead to the formation of mid-ocean ridges and volcanic activity. Conversely, when two plates are colliding (convergent boundary), it can result in the formation of mountains, earthquakes, and volcanic activity, such as subduction zones. Additionally, when two plates are sliding past each other (transform boundary), it can create faults and cause earthquakes. Therefore, the relative velocity between two plates is a crucial factor in determining the type and intensity of geologic activity at their boundary.