Answer:
Earthquaques
Step-by-step explanation:
Crustal plates are extremely heavy and thus impose tremendous pressure on adjacent plates, however they don't immediately slide past each other. Rather, tension is built up as time progresses and the pressure continues, until it is released and the plates slide rather abruptly to find their new position. The process starts over again because the plates do not stop moving. The internal heat in the core of the planet fuels their movement.