Based on INETER and SINAPRED reports, activity at Momotombo continued through 10 December. Fieldwork revealed a small, incandescent, circular crater halfway up Momotombo's E flank that was fuming during the morning on 6 December. An explosion on 7 December destroyed part of the crater. On 10 December SINAPRED reported that material had been accumulating in the crater since the beginning of the eruption on 1 December. Seismicity during 9-14 December was low and stable.

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.

Sources: Sistema Nacional para la Prevención, Mitigación y Atención de Desastres (SINAPRED), Instituto Nicaragüense de Estudios Territoriales (INETER)