2009 eruption

Based on satellite imagery, Nevados de Chillán volcano had an eruption in January 2009. An ash plume was detected that rose to 3.7-6.1 km (12,000-20,000 ft) altitude on 21-22 January and drifted 50-80 km SE.

2003 eruption

Small eruptions occurred for over the week ending 27 August 2003, with ash columns up to heights of 500 m. The eruptions produced a new double crater in the saddle between the cones Nuevo (which erupted during 1906-1945) and Arrau (which erupted during 1973-1986). Eruptions occurred at Las Termas subcomplex.

1861-65 eruptions

The eruptions between 1861-65 occurred on the NW flank of Cerro Blanco subcomplex from the Santa Gertrudis cone and produced a new lava field.
The main phase of the eruption occurred during August 1861, in the height of the Austral winter, when seasonal snow covered the upper flanks of the volcano. Powerful strombolian explosions sent incandescent bombs high into the sky and could be seen at night from Chillan town 80 km to the west. At the same time, strong ash eruptions occurred and an earthquake was felt in Chillan. Ash fall turned water cloudy in Nuble River 20 km to the north. On 22 August 1861, lava flows were erupted. From February 1862 until 1863, strombolian explosions continued with small lava fountains near the vent.
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Source:
K. Mee, H. Tuffen and J. S. Gilbert (2006) "Snow-contact volcanic facies and their use in determining past eruptive environments at Nevados de Chillán volcano, Chile", Bull. Volc., Volume 68, Number 4, 363-376