BackgroundVolcán Santo Tomás (also known as Volcán Pecul) is a large eroded stratovolcano located across a valley SE of Santa María volcano. The summit is capped by late-Quaternary andesitic tephra. A winding ridge connects it to Volcán de Zunil, 4.5 km NE, a stratovolcano that forms the topographic high point of the Santo Tomás-Zunil complex. Solfataras and thermal springs are located on the ridge's W side. Volcán de Zunil is located on the SW rim of the 4-km-wide, 600-m-deep Tzanjuyub caldera, which is breached to the S by the Río Masa. Several dacitic-rhyolitic lava domes are located on the caldera's N 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 at Santo Tomás are known, although the volcano was included in the Catalog of Active Volcanoes of the World (Mooser et al., 1958) based on its geothermal activity.
Source: Smithsonian / GVP volcano information
Santo Tomas Photos
See also: Sentinel hub | Landsat 8