General features at Masaya Caldera. Main pyroclastic cones are numbered
- Masaya is the most active volcano in
the region. The Spanish first described the volcano in 1524. Since then,
Masaya has erupted at least 19 times. From 1965 to 1979 Masaya contained
an active lava lake. The most recent eruption was in 1993. Masaya is
an unusual basaltic volcano because it has had explosive eruptions.
The eruption in 4550 B.C. was one of the largest on Earth in the last
Summit of Masaya cone.
- Masaya is a caldera (4 by 7 miles, 6
by 11.5 km) that contains 13 vents. Most activity at these vents consisted
of effusion of basaltic lava. Pyroclastic eruptions have constructed
three main cones: Masaya, Nindiri, and Santiago. Santiago formed in
1850-1853. Spatter and scoria deposits indicate fire fountaining at
Masaya, the only know occurrence of this type of eruption in Central
America (Williams, 1981).
- Unlike the stratovolcanoes that characterize
subduction zones, Masaya has a shield-like morphology.
- At times, Masaya emits large amounts
of sulfur dioxide gas. In 1981, sulfur dioxide was released from Santiago
Crater at a rate of 500,000 tons per year. Three periods of similar
gas activity occurred this century. Volcanologists studied these events
to better understand the impact of acid rain and the potential for health
- In 1979, Masaya became Nicaragua's first
National Park (Parque Nacional Volcan Masaya).
December 3, 1999
On 22 November, the Masaya Volcano appears
to have begun a new eruptive event. A hot spot has appeared on satellite
imagery, and there was a possible explosion.