Global Volcanism Program | Image GVP-10170
The western side of Coatepeque caldera at the top of the photo is seen from Cerro Chino cinder cone on the SE flank of Santa Ana volcano, which lies out of view to the left. The sloping rim of the caldera partially truncates the eastern side of Santa Ana. The western side of Coatepeque caldera is considered to have formed during the second stage of caldera formation associated with the eruption of the Congo Formation tephras and pyroclastic flows through a lake partially filling the earlier caldera.
Photo by Lee Siebert, 2002 (Smithsonian Institution).