Aerial view of the lobate laharic and lava flow units mantling the NNE flanks of Tacaná, the valley of San Rafael. Photo by Bill Rose, 1986.
Two major zones of this type of deposit were identified. One is on the west flank of the volcano, on the head of Río Agua Caliente. The other is on the south flank, between the Río Zapote and the area WNW of Talou (Mexico). A third, smaller, zone is identified on the ENE flank of Tacaná, near the head of the Río Las Majadas. Block and ashflow deposits of Tacaná are similar to those described for Fuego, and those produced by Santiaguito. Block and ashflows of relatively small volume are expected to be confined to talus aprons of domes and the valleys draining the slopes of Tacaná. Secondary explosions, similiar to those observed on ashflows from Fuego may occur within the ashflows, althought they represent little, if any, additional hazard.

Population centers threatened by this type of activity from Tacaná include La Laguna, San Rafael, La Vaga, Vega del Volcán, and Chocabj on the Guatemalan side of the volcano. In Mexico, Agua Caliente, Talquián, and Córdova are among those population centers possibly endangered by this type of activity. Additional hazards will affect areas downstream of ashflow as talus deposits dam the streams, thus giving rise to flooding and lahar generation.

(Mercado and Rose, 1992)