What occurs when two tectonic plates collide?

When two tectonic plates collide, several geological processes can occur simultaneously, as they can have complex interactions. The collision of tectonic plates often leads to subduction, where one plate is forced beneath another; this process contributes to the formation of deep ocean trenches and volcanic activity. Additionally, the intense pressure and stress that build up from the collision can result in earthquake activity, making it a common occurrence in regions where plates meet.

The collision can also lead to the formation of new crust in some scenarios, particularly in the case of continental-continental collisions where mountains are formed, or in other environments where the interacting plates create new geological structures.

Therefore, since these various processes can happen at the same time when two tectonic plates collide, the most comprehensive answer is that all of the mentioned phenomena—formation of new crust, subduction, and earthquake activity—can and often do occur together during such interactions.