No latest activity reported for Santo Tomás.

Below is a summary of eruption dates and Volcanic Explosivity Indices (VEI).

The following references are the sources used for data regarding this volcano. References are linked directly to our volcano data file. Discussion of another volcano or eruption (sometimes far from the one that is the subject of the manuscript) may produce a citation that is not at all apparent from the title. Additional discussion of data sources can be found under Volcano Data Criteria.

Carr M J, Rose W I Jr, 1987. CENTAM; a database of Central American volcanic rocks. {J Volc Geotherm Res}, 33: 239-240

Hughes J M, 1978. Geology and petrology of the Caldera Tzanjuyub, western Guatemala. {Unpublished Master's thesis}, Dartmouth College, 123 p

Hughes J M, Stoiber R E, Ide G M, Maynard S R, Mackay A M, 1980. Quaternary volcanism east of the Zunil Fault Zone, west Guatemala (abs). {Eos, Trans Amer Geophys Union}, 61: 69

Katsui Y (ed), 1971. List of the World Active Volcanoes. {Volc Soc Japan draft ms}, (limited circulation), 160 p

Mooser F, Meyer-Abich H, McBirney A R, 1958. Central America. {Catalog of Active Volcanoes of the World and Solfatara Fields}, Rome: IAVCEI, 6: 1-146

Newhall C G, 1987. Geology of the Lake Atitlan region, western Guatemala. {J Volc Geotherm Res}, 33: 23-55

Rose W I, 1987b. Volcanic activity at Santiaguito volcano, 1976-1984. {Geol Soc Amer Spec Pap}, 212: 17-27

Williams H, Meyer-Abich H, 1955. Volcanism in the southern part of El Salvador with particular reference to the collapse basins of Lakes Coatepeque and Ilopango. {Univ Calif Pub Geol Sci}, 32: 1-64

Volcán Santo Tomás (also known as Volcán Pecul) is a large eroded stratovolcano located across a valley SE of Santa María volcano. The summit of the volcano is capped by late-Quaternary andesitic tephra. A winding ridge connects Santo Tomás to Volcán de Zunil, 4.5 km to the NE, a 3542-m-high stratovolcano that forms the topographic high point of the Santo Tomás - Zunil complex. Volcán de Zunil is located on the SW rim of the 4-km-wide, 600-m-deep Tzanjuyub caldera, which is breached to the south by the Río Masa. Several dacitic-rhyolitic lava domes are located on the caldera's northern flank and the NW flank of Volcán de Zunil. The youngest dome, Cerro Zunil, was last active about 84,000 years ago (K-Ar dating). No Holocene eruptions are known from Santo Tomás, although it was included in the Catalog of Active Volcanoes of the World (Mooser et al., 1958) based on its geothermal activity. Solfataras and thermal springs are located on the west side of the ridge between Santo Tomás and Zunil.