The phrase "summit crater" refers to the hollow or bowl-shaped depression at the top of a volcano. It is formed when the volcano erupts, and the top part collapses inward, creating a hole where lava and gases are released. Full definition
The southernmost of two summit crater lakes, Botos, is cold and clear, and last erupted about 7,500 years ago. (enjoycentralamerica.com)
The colorful summit craters comprise a popular attraction, and are accessible by vehicle. (enjoycentralamerica.com)
Preceding that eruption, multiple earthquakes took place, followed by lava flowing down from the summit crater, before a major explosion took place on March 17 that year. (qz.com)