Final answer:
At divergent plate boundaries, earthquakes are typically shallow as these are zones where tectonic plates move apart and new crust is formed.
Therefore, the correct answer is: option a) Shallow only
Step-by-step explanation:
Earthquakes occur where tectonic plates interact with each other at plate boundaries. At divergent boundaries, earthquakes are typically shallow because this is where tectonic plates move away from each other and new crust is being created.
An earthquake is the sudden release of strain energy in the Earth's crust, resulting in waves of shaking that radiate outwards from the earthquake source. When stresses in the crust exceed the strength of the rock, it breaks along lines of weakness, either a pre-existing or new fault plane.
A divergent boundary occurs when two tectonic plates move away from each other. Along these boundaries, earthquakes are common and magma (molten rock) rises from the Earth's mantle to the surface, solidifying to create new oceanic crust.
This convergent boundaries, where earthquakes can occur at a range of depths due to one plate being forced under another in a process called subduction.