Magma exploding from a volcanohttps://www.nsf.gov/news/news_summ.jsp?cntn_id=126475
Volcanoes start within the mantle where magma forms. Magma is a hot rock that moves within the volcanoes mantle. Magma collects in the large pockets called the magma chambers. When it leaves the chamber, it moves up a tunnel and erupts.