Nevados de Chillán Volcano - John Seach



36.86 S, 71.37 W
summit elevation 3212 m

Nevados de Chillán Volcano is located in central Chile. The volcano lies in the Southern Volcanic Zone of the Andean Cordillera. The volcano of two compositionally distinct volcanic centres located 6 km apart on a NNW-SSE-trending axis.

Nevados de Chillán is a large composite stratovolcano constructed on a basement of granitic intrusive rocks and Cenozoic lavas. The main vents of the volcano extend along a 10 km long northwest trending ridge.

The eruptive history of the volcano spans interglacial and glacial periods.

Geology of Nevados de Chillán Volcano
Young parts of the volcano and associated lavas are divided into two subcomplexes about 6 km apart: the mainly andesitic Cerro Blanco subcomplex and the more silicic Las Termas subcomplex, separated by a saddle. Nevados de Chillán has produced magmas with compositions ranging from basaltic andesite to low-silica rhyolite.

Los Pincheira is a major group of subglacial andesite lava. The lava is relatively thick, flat-topped flows forming valley-side benches bounded by steep cliffs. The unit has an estimated remaining volume of 10 cubic km.

Volcán Viejo is the oldest of the summit crater structures and is associated with Pata de Perro satellite cone and lava on the eastern flank. Volcán Chillán is a dacitic
stratocone, located on SW crater-rim of Volcán Viejo, and produced blocky dacite flows on the southern and SW flanks.

2009 Eruptions
On 21st January 2009, continuous emissions were reported at the volcano. Ash emissions reached 12,000 ft altitude.

2003 Eruptions
In 2003 there were small eruptions for a week, with ash columns up to heights of 500 m. The eruptions formed a new double crater in the saddle between Nuevo and Arrau cones. Eruptions occurred at Las Termas subcomplex.

1973–1986 Eruptions
Eruptions occurred at Las Termas subcomplex.

Eruptions between 1906 and 1948 occurred at Las Termas subcomplex.

1861-65 Eruptions
The eruptions occurred at Cerro Blanco subcomplex and formed the Santa Gertrudis lava field. The main phase of the eruption occurred during August 1861 when seasonal snow covered the upper flanks of the volcano. Ejected bombs were seen at night from Chillan (80 km west). Explosive eruptions began and an earthquake was felt in Chillan. Tephra fall turned water cloudy in Nuble River, 20 km north. On 22nd August 1861 lava flows began. From February 1862 until 1863 Strombolian explosions continued with small lava fountains near the vent.

Nevados de Chillán Volcano Eruptions

2009, 2003, 1973-86, 1972, 1965, 1946-48, 1945, 1934, 1929, 1923, 1906, 1898, 1891, 1883, 1877, 1872, 1861-65, 1752, 1750-51, 1650