The area that forms around a volcano's central opening is called the crater.

Here's a breakdown:

* Crater: A bowl-shaped depression at the summit of a volcano, formed by the eruption of volcanic material. It's the opening through which the volcano expels lava, ash, and gases.

* Vent: The actual opening within the crater that connects to the magma chamber below.

It's important to note that:

* Calderas: Are much larger depressions than craters, formed by the collapse of a volcano's summit after a massive eruption.

* Summit: Refers to the highest point of the volcano, which may or may not have a crater or caldera.