Question

Can anyone tell me how an impact crater is formed?

Answer 1

Craters come in two flavors: those that aren't caused by asteroids or comets, impact craters, are formed by powerful volcanic explosions. Such outbursts can be violent enough that once the eruption is over, the volcano collapses in on its empty vacant magma chamber and forms a caldera, or volcaniccrater.
hope this will help u

Answer 2

it is formed by the powerful volcanic explosion