INETER reported that on 7 June seven explosions at San Cristóbal ejected gas and ash, and were detected by the seismic station located on the W flank. The explosions occurred at 0615, 0645, 0653, 0911, 1137, 1139, and 1143, and were also observed by civil defense and INETER staff. The largest explosion, at 1139, generated a plume that rose 100 m. Sulfur dioxide emissions, which had been low, increased. A report later that afternoon stated that gas-and-ash explosions decreased, but Real-time Seismic-Amplitude Measurement (RSAM) values almost tripled to between 80 and 100 units due to increased tremor. INETER noted that tremor is frequently detected at San Cristóbal, and for the public not to be alarmed. A small lahar occurred at 1710.

Geological Summary. The San Cristóbal volcanic complex, consisting of five principal volcanic edifices, forms the NW end of the Marrabios Range. The symmetrical 1745-m-high youngest cone, named San Cristóbal (also known as El Viejo), is Nicaragua's highest volcano and is capped by a 500 x 600 m wide crater. El Chonco, with several flank lava domes, is located 4 km W of San Cristóbal; it and the eroded Moyotepe volcano, 4 km NE of San Cristóbal, are of Pleistocene age. Volcán Casita, containing an elongated summit crater, lies immediately east of San Cristóbal and was the site of a catastrophic landslide and lahar in 1998. The Plio-Pleistocene La Pelona caldera is located at the eastern end of the complex. Historical eruptions from San Cristóbal, consisting of small-to-moderate explosive activity, have been reported since the 16th century. Some other 16th-century eruptions attributed to Casita volcano are uncertain and may pertain to other Marrabios Range volcanoes.

Source: Instituto Nicaragüense de Estudios Territoriales (INETER)