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Los Humeros Volcano | John Seach
Mexico
19.68 N, 97.45 W
summit elevation 3150 m
Calderas
Los Humeros Volcano is located north of the main Mexican volcanic belt, 180 km west of Mexico city.
Los Humeros volcanic center is located near the east end of the Mexican Neovolcanic Belt, 55 km west-northwest of the city of Xalapa, Veracruz. The Los Humeros caldera is about 400 m deep and is irregularly circular with a diameter 21 km x 15 km.
Los Humeros caldera was formed in a large eruption 460,000 years ago. A second caldera was formed 100,000 years ago and was followed by a third caldera formation 20,000-40,000 years ago.
Geothermal activity is present at the volcano. Fumarolic activity and sulfur deposits
are observed in the oval-shaped La Calderita crater located in the southern part of Los Humeros caldera. This caldera formed as a result of the collapse of the root of the magma chamber.
Los Humeros magma is broadly similar in chemical composition to those from other areas of the Mexican volcanic belt. There are small differences are however apparent
for some elements. Los Humeros basalts have higher MgO and lower K2O. Basaltic andesites from Los Humeros are richer in Al2O3 whereas andesites show higher TiO2 and lower MgO. Dacites and rhyolites from Los Humeros have considerably lower FeO than those from other areas of the Mexican Volcanic Belt.
Eruptions at Los Humeros Volcano
1) Silicic volcanism began at Los Humeros volcano 47,000 years ago with extrusion of high-silica rhyolite domes.
2) This was followed by eruption of 115 cubic km of magma 47,000 years ago, forming the Xaltipan Ignimbrite. Pyroclastic flows covered 3500 sq km, and descended to an elevation of 1900 m over a distance of 50 km. The Xaltipan Ignimbrite is covered by a co-ignimbrite ash-fall deposit, which is covered by eight air-fall lapilli tuffs. Eruption of the Xaltipan Ignimbrite led to collapse of the Los Humeros caldera. Several high-silica rhyolite domes were emplaced after caldera collapse at or close to the inferred Los Humeros ring-fracture zone.
3) Faby Tuff was erupted 24,000 years ago, producing 10 cubic km of lava, and airfall deposits.
4) Zaragoza Tuff erupted 12 cubic km of lava 100,000 years ago. This led to the collapse of the 10-km diameter Los Potreros caldera, which is nested within the
older Los Humeros caldera.
5) Xoxoctic Tuff erupted 50,000 years ago.
6) Between 40,000 and 30,000 years ago, an arc of andesitic scoria cones formed along the southern ring-fracture zone of the Los Humeros caldera. These deposits are covered by Cuicuiltic Tuff. This was followed by collapse of the 1-7-km diameter El Xalapazco caldera.
7) Eruptions continued at Los Humeros Volcano until 20,000 years ago, with emission of small volumes of olivine basalt erupted along the southern ring-fracture zone of the Los Humeros caldera and on the floors of the Los Potreros and El Xalapazco calderas.
Los Humeros Volcano Eruptions
20,000 years ago.