Report on Masaya (Nicaragua) — June 1997
Bulletin of the Global Volcanism Network, vol. 22, no. 6 (June 1997)
Managing Editor: Richard Wunderman.
Masaya (Nicaragua) Stable and non-eruptive during May-June
Please cite this report as:
Global Volcanism Program, 1997. Report on Masaya (Nicaragua) (Wunderman, R., ed.). Bulletin of the Global Volcanism Network, 22:6. Smithsonian Institution. https://doi.org/10.5479/si.GVP.BGVN199706-344100.
11.984°N, 86.161°W; summit elev. 635 m
All times are local (unless otherwise noted)
Besides the strong degassing and high tremor, which are normal for this volcano, Masaya lacked signs of abnormal activity during May and June 1997.
Geologic Background. Masaya is one of Nicaragua's most unusual and most active volcanoes. It lies within the massive Pleistocene Las Sierras pyroclastic shield volcano and is a broad, 6 x 11 km basaltic caldera with steep-sided walls up to 300 m high. The caldera is filled on its NW end by more than a dozen vents that erupted along a circular, 4-km-diameter fracture system. The twin volcanoes of Nindirí and Masaya, the source of historical eruptions, were constructed at the southern end of the fracture system and contain multiple summit craters, including the currently active Santiago crater. A major basaltic Plinian tephra erupted from Masaya about 6500 years ago. Historical lava flows cover much of the caldera floor and have confined a lake to the far eastern end of the caldera. A lava flow from the 1670 eruption overtopped the north caldera rim. Masaya has been frequently active since the time of the Spanish Conquistadors, when an active lava lake prompted attempts to extract the volcano's molten "gold." Periods of long-term vigorous gas emission at roughly quarter-century intervals cause health hazards and crop damage.
Information Contacts: Wilfried Strauch, Department of Geophysics, and Marta Navarro C., Department of Volcanoes, Instituto Nicaragüense de Estudios Territoriales (INETER), P.O. Box 1761, Managua, Nicaragua.