Where does most seismic activity occur?

Most of seismic activity occur at the boundaries of tectonic plates.

Explanation:

Tectonic plates are in constant movement.

The movements of these plates result in the following types of limits:

Small earthquakes are associated with convergent boundaries, and larger ones with divergent and transform.

The vast majority of the largest and most catastrophic earthquakes in history have occurred near the boundaries of tectonic plates.

heat from the core of the earth causes convection currents to occur in the mantle. these currents slowly move the crust around.