The Crater
Inside the Crater: Villarrica's Lava Lake
Villarrica is one of a handful of volcanoes on Earth with an active lava lake, and one of very few you can legally stand above.
Check dates and availability ↗Villarrica volcano — geological reference
| Feature | What is known |
|---|---|
| Summit crater | Approximately 200 m across |
| Lava lake | Active but intermittent; one of a small number worldwide known to hold one |
| Magma composition | Dominantly basaltic to basaltic-andesite |
| Glacier cover | Approximately 40 km² |
| Underlying caldera | A 2 km-wide caldera formed about 3,500 years ago |
| Flank features | More than 30 scoria cones and fissure vents |
| Documented eruptions | At least 74 since 1558 CE |
| Mapuche name | Rucapillán / Ruka Pillañ — house of the spirit |
A rare kind of summit
Most volcanoes, even very active ones, do not hold an open lake of molten rock. Villarrica does — intermittently, but persistently enough that it is counted among the small handful of volcanoes worldwide known to sustain an active lava lake within the summit crater. It has maintained a high magma column with periodic strombolian episodes since the early 1980s. What makes it unusual for a traveller is the combination: a rare geological phenomenon at the top of a walkable, guided, single-day route from a town with hotels and restaurants.
What you actually see at the rim
Manage your expectations here, because accurate reporting matters more than a good photograph. The crater is roughly 200 metres across, and what you look down into depends entirely on the volcano's mood and the wind. On a favourable day the gas clears and you see glowing, incandescent material and hear the volcano working. On many days the vent is obscured by a dense plume and you see white and yellow murk, feel heat, and smell sulphur. Night-time incandescence visible from Pucón is a separate and more reliable spectacle from the town below.
The gas plume
Villarrica emits a continuous plume dominated by sulphur dioxide, and the crater rim is the point of maximum exposure. This is why filter masks are issued and why their use near the crater is treated as compulsory, and it is a substantial part of the reasoning behind CONAF's 30-minute cap on summit time. The gas irritates eyes and airways, and its concentration at any moment is set by wind direction rather than by the volcano's alert level. A green alert does not mean a benign summit atmosphere.
The volcano beneath the tourism
Villarrica is a glacier-covered stratovolcano in the northern Lake District, about 15 kilometres south of Pucón, with roughly 40 square kilometres of glacier on its flanks. The present cone grew at the northwest margin of a 6-kilometre-wide Pleistocene caldera, and a further 2-kilometre-wide caldera formed at its base around 3,500 years ago. More than 30 scoria cones and fissure vents dot the flanks, evidence that eruptions here have not always come from the summit.
An eruption record going back to 1558
Villarrica has one of the longest documented eruption records in South America, with eruptions recorded since 1558 CE and at least 74 historical eruptive episodes catalogued. Since 1900 alone, eruptive activity has been recorded in 71 of 127 years. Historically these have been largely mild to moderate explosive events with occasional lava effusion, punctuated by more significant episodes such as March 2015. This is a working volcano with an unbroken habit of working.
Lahars — the hazard that reaches the towns
For the communities around the volcano, the defining danger is not the crater but what the crater melts. Villarrica carries a large glacier and heavy seasonal snow; heat from an eruption can mobilise that ice into lahars, fast-moving flows of meltwater, ash and debris that follow river valleys for many kilometres. The record is unambiguous: lahars killed 27 people at Coñaripe in 1964, and the 1971–72 eruption produced lahars with at least 15 deaths. Evacuation planning and marked lahar routes around Pucón exist because of this specific hazard.