A temporary increase in tremor and very small earthquakes occurred at Cerro Negro during 19 February at 2300 to 20 February at 1100. During a visit to the volcano on the 20th, INETER and Civil Defense personnel noted no important changes in activity in comparison to their previous visit on 16 February. They found a small 80- to100-m-long and 45-m-wide landslide, a new fumarole, fumarole temperatures that were slightly higher than normal, and a large amount of sulfur deposited on many fumaroles. According to INETER, the increase in tremor was possibly due to a temporary increase in volcanic gas emission related to the formation of the new fumarole. They stated that the population near Cerro Negro was not in direct danger, although people should be aware of the possibility of unexpected events.

Geological Summary. Nicaragua's youngest volcano, Cerro Negro, was created following an eruption that began in April 1850 about 2 km NW of the summit of Las Pilas volcano. It 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. Strombolian-to-subplinian eruptions at intervals of a few years to several decades have constructed a roughly 250-m-high basaltic cone and an associated lava field constrained by topography to extend primarily NE and SW. Cone and crater morphology have varied significantly during its short eruptive history. Although it lies in a relatively unpopulated area, occasional heavy ashfalls have damaged crops and buildings.

Sources: La Prensa (Nicaragua), Instituto Nicaragüense de Estudios Territoriales (INETER), La Prensa (Nicaragua)