SINAPRED reported that on 5 July a small explosion at San Cristóbal produced a moderately-sized ash-and-gas plume. The emissions in photos posted by SINAPRED appeared to be dense and gray, and pyroclastic flows were visible on the upper flanks. According to news articles, a strong sulfur odor was reported in nearby communities along with the fall of ash and larger tephra, most notably in La Grecia (12 km WSW). Fine ash particles in the air ash continued to impact residents the next day. A dark narrow deposit extending about 10 km W from the summit crater was visible in a 9 July Sentinel satellite image.

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.

Sources: Sistema Nacional para la Prevención, Mitigación y Atención de Desastres (SINAPRED), La Prensa (Nicaragua), Sentinel Hub, European Pressphoto Agency