Chillan, Nevados de (Chile): Recorded Eruptions and Historical Activity

Nevados de Chillán is a stratovolcano located in Chile, reaching an elevation of 3,180 meters within a subduction zone and continental crust tectonic setting. Official records from the Smithsonian Global Volcanism Program document 26 confirmed eruptions across a broad timeline, stretching from prehistoric radiocarbon-dated activity in 6890 BCE up to structured records in the 21st century CE.

The historical record distinguishes individual eruptive episodes across different vents and craters, such as Volcán Viejo, Cerro Blanco, and the Nicanor crater. Evidence methods for these events range from early isotopic and uncalibrated radiocarbon data for ancient periods to direct human observations and reported accounts for more recent centuries.

Overview of Recorded Eruption Chronology

The confirmed eruption count of 26 is distributed unevenly across centuries, reflecting both the actual geological behavior of the volcano and the varying levels of historical observation over time. The earliest recorded event is estimated at 6890 BCE with a 500-year uncertainty range. Subsequent activity spans multiple eras:

• Ancient and Pre-Columbian Eras: Eruptions are recorded in the 69th century BCE, 4th century BCE, and 16th century BCE.
• Historical Eras: Activity picked up considerably in later centuries, with 1 recorded eruption in the 17th century CE, 2 in the 18th century CE, 8 in the 19th century CE, and 9 in the 20th century CE.
• Modern Era: The 21st century CE has accounted for 2 confirmed eruptions thus far in the structured record.

Notable Historical Eruptions and Intensity

Where data permits, the Volcanic Explosivity Index (VEI) provides a relative measure of the explosiveness of individual eruptions. Out of the 26 confirmed eruptions, 22 include VEI observations. The largest recorded VEI in the official record for Nevados de Chillán is 3.0.

For example, a confirmed eruption originating from the northwest flank of Cerro Blanco (Santa Gertrudis) began on November 30, 1864, and ended on February 3, 1865, reaching a VEI of 3.0 based on reported observations. Other events, such as the activity at Cerro Blanco and Volcán Viejo on January 30, 1752, and at Volcán Viejo on February 16, 1891, recorded lower explosivity levels with a VEI of 2.0.

More recently, activity at the Nicanor crater began on January 8, 2016, with a VEI of 2.0, and concluded on October 17, 2022. While the profile's last known eruption year in the database is 2022, the structured record indicates that individual events have distinct start and end parameters documented through reported observations.