INETER reported that during 16-17 February two explosions at Momotombo were accompanied by tremor, and produced ash emissions and ejected incandescent material onto the flanks. The first and largest explosion (recorded at 0344) ejected incandescent tephra 800 m above the crater. RSAM values were at low-to-moderate levels. Based on webcam views and satellite images, the Washington VAAC reported that on 19 February ash emissions rose to an altitude of 3.6 km (12,000 ft) a.s.l. and drifted SW and WSW. The next day ash emissions drifted SW. On 21 February ash plumes drifted about 80 km W and 25 km E.

Geological Summary. Momotombo is a young stratovolcano that rises prominently above the NW shore of Lake Managua, forming one of Nicaragua's most familiar landmarks. Momotombo began growing about 4500 years ago at the SE end of the Marrabios Range and consists of a somma from an older edifice that is surmounted by a symmetrical younger cone with a 150 x 250 m wide summit crater. Young lava flows extend down the NW flank into the 4-km-wide Monte Galán caldera. The youthful cone of Momotombito forms an island offshore in Lake Managua. Momotombo has a long record of Strombolian eruptions, punctuated by occasional stronger explosive activity. The latest eruption, in 1905, produced a lava flow that traveled from the summit to the lower NE base. A small black plume was seen above the crater after a 10 April 1996 earthquake, but later observations noted no significant changes in the crater. A major geothermal field is located on the south flank.

Source: Instituto Nicaragüense de Estudios Territoriales (INETER)