The large barren area is a volcanic crater, I believe it's Napau Crater.  I often think of craters as being a large hole at the top of a mountain.  While I have seen craters like that (notably Mt. Ngauruhoe in New Zealand), Hawaiian craters can be flattened areas as you see here.  The mountain in the background is Pu’u’o’o.  It's more of a volcanic cone or at least it used to be until the cone collapsed.  Also, you can see,  the sides of it are sort of missing.  Must have been having a very bad day or something.