Report on Apoyo (Nicaragua) — February 1991
Bulletin of the Global Volcanism Network, vol. 16, no. 2 (February 1991)
Managing Editor: Lindsay McClelland.
Apoyo (Nicaragua) No fumarolic or seismic activity
Please cite this report as:
Global Volcanism Program, 1991. Report on Apoyo (Nicaragua) (McClelland, L., ed.). Bulletin of the Global Volcanism Network, 16:2. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199102-344802.
11.92°N, 86.03°W; summit elev. 600 m
All times are local (unless otherwise noted)
"No fumarolic or seismic activity was detected in 1990."
Geologic Background. The scenic 7-km-wide, lake-filled Apoyo caldera is a large silicic volcanic center immediately SE of Masaya caldera. The surface of Laguna de Apoyo lies only 78 m above sea level; the steep caldera walls rise about 100 m to the eastern rim and up to 500 m to the western rim. An early shield volcano constructed of basaltic-to-andesitic lava flows and small rhyodacitic lava domes collapsed following two major dacitic explosive eruptions. The caldera-forming eruptions have been radiocarbon dated between about 21,000-25,000 years before present. Post-caldera ring-fracture eruptions of uncertain age produced lava flows below the scalloped caldera rim. The slightly arcuate, N-S-trending La Joya fracture system that cuts the eastern flank of the caldera only 2 km east of the caldera rim is a younger regional fissure system structurally unrelated to Apoyo caldera.
Information Contacts: B. van Wyk de Vries, O. Castellón, A. Murales, and V. Tenorio, INETER.