Deep-focus earthquakes form at subduction zones as well as continental-continental plate boundaries. The given statement is true statement.
Step-by-step explanation:
Because deep- focus earthquakes will occur within the areas of deeper subduction zones, where subduction zones also has intense volcanic eruptions .
subduction zones are created due to the converging of continental plates and when it collide each other,the earthquakes developed are deeper and very powerful. If collisions is numerous results in large earthquakes.