Volcano Type: Cinder cones
Volcano Status: Historical
Last Known Eruption: 1999
Summit Elevation: 728 m 2,388 feet
Latitude: 12.506°N 12°30’22″N
Longitude: 86.702°W 86°42’7″W
Central America’s youngest volcano, Cerro Negro, was born in April 1850 and has since been one of the most active volcanoes in Nicaragua. Cerro Negro is the largest, southernmost, and most recent of a group of four youthful cinder cones constructed along a NNW-SSE-trending line in the central Marrabios Range 5 km NW of Las Pilas volcano. Strombolian-to-subplinian eruptions at Cerro Negro at intervals of a few years to several decades have constructed a roughly 250-m-high basaltic cone and an associated lava field that is constrained by topography to extend primarily to the NE and SW. Cone and crater morphology at Cerro Negro have varied significantly during its eruptive history. Although Cerro Negro lies in a relatively unpopulated area, its occasional heavy ashfalls have caused damage to crops and buildings in populated regions of the Nicaraguan depression.
Cerro Negro is a very active, nascent composite cone, born in 1850. Its eruptions are part lava, part tephra, with lots of ash size tephra. Cerro Negro’s basaltic lavas have water contents of up to 6%. These very high water contents make the eruptions very explosive, so the magmatic froth produced is highly fractured and shattered to tiny particles. Because basalts are hot, about 1200C, they are very fluid (low viscosity), which allows gas to segregate from the magma easuly. This allows simultaneous gas-rich explosions in the central vent and gas-poor lava effusions on the flank. The model of composite volcanoes that has alternating layers of tephra and lava, seems appropriate for Cerro Negro, although it is only an infant.
Cerro Negro’s eruptions commonly occur in clusters that coincide with tectonic earthquakes. The current eruption sequence began in 1992, a few month prior to a major, tsunamigenic earthquake, immediately offshore from the volcano. The previous eruption cluster, 1968-1971 preceeded the Managua Earthquake of 1972, a shallow, strike-slip earthquake that destroyed the downtown of Nicaragua’s capital. The initial eruptions of Cerro Negro coincided with a great Nicaraguan earthquake in 1850. Cerro Negro appears to be a sensitive strain meter.
Originally posted 2010-08-24 04:15:07.
