CHILLÁN — Nevados de Chillán volcano erupted with an explosion on Apr. 8. This was one of the largest of its eruptions in the current cycle that started four years ago. All is relatively calm now, but authorities continue to keep a watchful eye on the volcano.
Those not in quarantine around the Chillán area, those working at OVDAS (the Chilean national volcano monitoring network), and those watching the OVDAS cameras at home, may have had the pleasure of experiencing a powerful explosion from the Nevados de Chillan volcanic complex on Apr. 8.
Just before 6 p.m. that day, the volcano blew its top in what was one of the largest explosions in the current cycle of activity that has lasted since January 2016. The explosion formed a column of hot ash and gas that rose up to 3.7 km from the volcano’s summit. Most of the ash fell to the south of the volcano, but some small pyroclastic density currents (gravity driven clouds of hot ash and gas) also rolled down the volcano’s flanks. There was also a small earthquake.
ÚLTIMA HORA 🌋 | Gran pulso eruptivo moderado a fuerte en el cráter Nicanor del Nevados de #Chillán, con una columna de cenizas que se extiende aproximadamente a los 3 kilómetros de altura, a las 17:54 hrs.
— Red Geocientífica de Chile (@RedGeoChile) April 8, 2020
The volcano remains at alert level yellow, which has been the case since it started showing signs of increased activity almost five years ago in December 2015. An exclusion zone of 2 km around the volcano’s summit remains in force as further explosions are likely over the coming weeks and months.
The Nevados de Chillán volcano consists of several different peaks and has been active and growing for more than half a million years. Prior to the start of the 2016 eruptive cycle, which has experienced numerous small explosions from one of the summit craters, the volcano last erupted in 1973.
The dangerous part of the volcano seems to be the main active central vent and the volcano’s slopes, hence the modest 2 km exclusion zone. However, in the past, eruptions have emanated from other sections of the complex. While there is no suggestion from the monitoring data that other parts of the volcanic complex will experience an imminent eruption there is always potential for the activity to shift.
The volcano is monitored by an array of ground displacement monitoring stations and seismometers which detect changes in the shape of the volcano and listen for ground tremors, but it is very difficult to forecast explosions such as the one that just occurred.
A primary concern is if the volcanic activity migrates to a different part of the complex or if the explosions are larger and, hence, affect a bigger area. OVDAS and SERNAGEOMIN (the Chilean national geology and mining service) continue to monitor ongoing activity to look for signs predictive of either.
John is a volcanologist, sports fan, radio broadcaster, and accomplished musician. Born and raised in Britain, he has travelled extensively for his research on volcanoes. Whilst living in London, UK, John performed in the punk bands ‘And Now We’re Even’ and ‘Filthy Militia’ recording six studio albums and two EP’S over this time. He currently lives in Santiago, Chile where he works as a university professor in rock mechanics.