Question

why are earthquakes and volcnic eraption called endogenic factors

Answer 1

 Because these are occurred by the processes present beneath the surface of the earth. Because the origin of the cause of these processes takes place inside the Earth.

Answer 2

Because earthquakes and volcanoes have internal origins. The processes originating externally are called the exogenic processes (weathering, for example). Magma originates at the crust mantle boundary and rises up through the fissures/cracks or vents as ‘lava’. Faulting or rupture of plates, produce seismic waves which give rise to earthquakes on the surface.