SfondoApoyeque is part of the Chiltepe pyroclastic shield volcano, one of 3 large ignimbrite shields on the Nicaraguan volcanic front. The caldera formed after a VEI 6 plinian eruption which left a thick mantle of dacitic pumice that blankets the surrounding area (Chiltepe Tephra).
Other features of the volcano include:
The Talpetatl lava dome was constructed between Laguna Xiloá and Lake Managua.
Pumiceous pyroclastic flows from Laguna Xiloá were erupted about 6100 years ago and overlie deposits of comparable age from the Masaya plinian eruption.
Source: Smithsonian / GVP Apoyeque volcano information
See also: Sentinel hub | Landsat 8 | NASA FIRMS