Volcanoes in Ecuador

Ecuador has 35 Holocene volcanoes, comprising 21 along the mainland Andean volcanic arc and 14 in the [[country:ecuador|Galápagos Islands]] archipelago roughly 1,000 km to the west, making it one of the most volcanically dense nations on Earth relative to its land area. The country's volcanic heritage is so central to its geography that the famous "Avenue of Volcanoes" — a name coined by the German explorer Alexander von Humboldt in 1802 — describes the twin cordillera of peaks flanking the Interandean Valley between Quito and Riobamba. Ecuador's tallest peak, [[volcano:chimborazo|Chimborazo]] at 6,261 m (20,541 ft), is also the point on the Earth's surface farthest from the planet's center, owing to the equatorial bulge.

Among the most active volcanoes in South America, [[volcano:cotopaxi|Cotopaxi]], [[volcano:sangay|Sangay]], and [[volcano:reventador|Reventador]] have all erupted within the past decade, while [[volcano:tungurahua|Tungurahua]] maintained a 17-year eruptive cycle from 1999 to 2016. In total, 360 eruptions are recorded across Ecuadorian volcanoes in the Smithsonian database, spanning a VEI range from 0 to 6. The most explosive known event was the VEI 6 eruption of [[volcano:quilotoa|Quilotoa]] around 1280 CE, which generated pyroclastic flows reaching the Pacific lowlands over 80 km away.

Ecuador's volcanic hazards directly threaten major population centers: Quito (population 2.8 million) sits between the active cones of Guagua Pichincha to the west and Cotopaxi 60 km to the southeast, placing it among the most volcanically exposed capital cities on the planet.

Ecuador's intense volcanic activity is driven by two entirely distinct tectonic mechanisms operating within the same national territory. On the mainland, the Nazca Plate subducts beneath the South American Plate along the Peru–Chile Trench at a rate of approximately 58 mm per year. As the dense oceanic crust descends into the mantle, it releases water and volatiles that lower the melting point of the overlying mantle wedge, generating magma that rises to feed the volcanoes of the Northern Volcanic Zone (NVZ) of the Andes.

This subduction produces predominantly andesitic and dacitic magmas — viscous, gas-rich compositions that favor explosive eruptions. Ecuador's Andean volcanoes are built on extremely thick continental crust exceeding 25 km, which further modifies magma composition as it ascends through and assimilates crustal rock. The NVZ stretches roughly 300 km from Soche near the Colombian border to Sangay in the south, forming two parallel chains: the Western Cordillera (including Chimborazo, Atacazo, and Guagua Pichincha) and the Eastern Cordillera or Cordillera Real (including Cotopaxi, Antisana, and Tungurahua).

A small back-arc chain farther east includes Reventador, Sumaco, and the isolated Pan de Azúcar — volcanoes erupting more alkaline, under-saturated lavas unusual for the Andean setting.

The [[country:ecuador|Galápagos Islands]], by contrast, are not related to subduction at all. They are formed by the Galápagos mantle plume, a column of abnormally hot material rising from deep within the mantle beneath the Nazca Plate. As the plate moves eastward over this fixed hotspot at roughly 51 mm per year, successive shield volcanoes are built and then carried away, creating a chain of islands whose age increases from west to east. [[volcano:fernandina|Fernandina]], sitting nearly above the plume center, is the most active, while the eastern islands such as San Cristóbal are older and largely extinct.

The Galápagos spreading center to the north adds a rift-zone component, further complicating the tectonic picture. This dual-mechanism volcanism gives Ecuador an extraordinary diversity of eruption styles: explosive Plinian eruptions on the mainland and effusive basaltic shield eruptions in the Galápagos, all within a single country. Iceland is the only other nation where a comparable intersection of a divergent plate boundary and a mantle plume produces such volcanic variety — though Iceland's mechanism differs in that it lies on a mid-ocean ridge rather than at a subduction zone.

**Cotopaxi (5,911 m / 19,393 ft)**

[[volcano:cotopaxi|Cotopaxi]] is Ecuador's most iconic volcano and one of the world's highest active [[special:types-of-volcanoes|stratovolcanoes]]. Its near-perfect glacier-clad cone, topped by a 550 × 800 m summit crater, has produced 86 recorded eruptions including eight VEI 5 events extending back to 5820 BCE. The most devastating historical eruption occurred in 1877, when pyroclastic flows melted glacial ice and spawned lahars that traveled more than 100 km into both the Pacific coastal lowlands and the Amazon basin.

After over seven decades of quiet, Cotopaxi reawakened in 2015 and has shown intermittent activity through 2023, prompting renewed evacuation planning for the 300,000 people living in potential lahar paths. It is the most closely monitored volcano in Ecuador, instrumented by the Instituto Geofísico of the Escuela Politécnica Nacional (IG-EPN).

**Chimborazo (6,261 m / 20,541 ft)**

[[volcano:chimborazo|Chimborazo]], the highest peak in Ecuador and the farthest point from Earth's center, anchors the southern end of the Avenue of Volcanoes. Despite its immense size, Chimborazo is relatively quiet — its six recorded eruptions are all prehistoric, with the most recent dated to approximately 550 CE. The volcano experienced a catastrophic sector collapse around 35,000 years ago that sent a massive debris avalanche toward the site of modern Riobamba.

**Tungurahua (5,023 m / 16,480 ft)**

[[volcano:tungurahua|Tungurahua]], the "Throat of Fire" in Kichwa, rises more than 3 km above the tourist town of Baños at its northern base. Its 16-year eruptive episode from 1999 to 2016 forced repeated evacuations, produced pyroclastic flows, and deposited ash across central Ecuador. With 37 recorded eruptions and a maximum VEI of 5, Tungurahua ranks among the most hazardous volcanoes in South America due to the proximity of Baños (population ~20,000) to its steep flanks.

**Guagua Pichincha (4,784 m / 15,696 ft)**

[[volcano:guagua-pichincha|Guagua Pichincha]] lies immediately west of Quito, making it one of the most closely watched volcanoes in the world. Its 44 recorded eruptions include three VEI 5 events. The 1999 eruption deposited ash across the capital and prompted emergency evacuations.

A 6-km-wide collapse scarp from a late-Pleistocene slope failure dominates the summit area, within which an active lava dome grows and is periodically destroyed.

**Sangay (5,286 m / 17,339 ft)**

[[volcano:sangay|Sangay]], the southernmost and one of the most persistently active volcanoes in Ecuador, has been in near-continuous eruption since 1628 with varying intensity. Its remote location east of the Andean crest, rising above the Amazonian rainforest, means that eruptions often go unobserved except by satellite. Sangay's 11 recorded eruptions include a VEI 3 event, and its continuous Strombolian and Vulcanian activity makes it one of the most active volcanoes in the Americas.

**Reventador (3,562 m / 11,686 ft)**

[[volcano:reventador|Reventador]], lying well east of the main volcanic axis in the sub-Andean zone, is Ecuador's most frequently erupting volcano in the 21st century. Its spectacular VEI 4 eruption in November 2002 sent an ash column 17 km high and deposited up to 5 mm of ash on Quito 90 km away. Since 2002, Reventador has been in near-continuous eruptive activity, making it one of the most consistently active volcanoes on Earth.

The volcano sits within a 4-km-wide amphitheater formed by an earlier edifice collapse.

**Quilotoa (3,914 m / 12,841 ft)**

[[volcano:quilotoa|Quilotoa]] produced Ecuador's largest known Holocene eruption — a VEI 6 event around 1280 CE that generated voluminous pyroclastic flows and lahars reaching the Pacific coast. Today, the 3-km-wide caldera filled by a striking turquoise-green lake is one of Ecuador's most visited natural attractions and a highlight of the popular Quilotoa Loop trekking circuit.

**Fernandina (1,476 m / 4,843 ft)**

[[volcano:fernandina|Fernandina]], the youngest and most active of the Galápagos shield volcanoes, sits closest to the mantle plume and has produced 33 recorded eruptions with a maximum VEI of 4. Its 5 × 6.5 km summit caldera experienced a dramatic 350-m collapse in 1968. Fernandina's eruptions are typically effusive, producing fluid basaltic lava flows from both summit and radial flank fissures, in sharp contrast to the explosive activity of mainland Ecuadorian volcanoes.

**Wolf (1,710 m / 5,610 ft)**

[[volcano:wolf|Wolf]], the tallest volcano in the Galápagos, straddles the equator at the northern tip of Isabela Island. Its 6 × 7 km caldera is 700 m deep. Wolf has erupted 17 times, most recently in January 2022, when lava flows prompted concern for the habitat of the critically endangered pink iguana endemic to the volcano's northern slopes.

**Sierra Negra (1,124 m / 3,688 ft)**

[[volcano:negra-sierra|Sierra Negra]], with the largest caldera in the Galápagos (7 × 10.5 km), is a broad shield volcano at Isabela's southern end. Its 2018 eruption was preceded by dramatic uplift — the caldera floor rose over 5 m in the months before lava breached the caldera rim, one of the largest pre-eruptive deformation signals ever recorded.

**Cayambe (5,790 m / 18,996 ft)**

[[volcano:cayambe|Cayambe]] is the only volcano on Earth whose summit is crossed by the equator, and at 5,790 m it is the highest point on the equatorial line. Its 22 eruptions include a VEI 4 event. The glacier-capped compound volcano last erupted in 1786 and is considered a significant lahar hazard to communities along its flanks.

Ecuador's eruption record spans at least 8,000 years, with 360 eruptions documented across its 35 Holocene volcanoes. The most explosive known event is the VEI 6 eruption of Quilotoa around 1280 CE, which ejected dacitic pyroclastic flows that traveled over 80 km to the Pacific coast and sent lahars down the Toachi River drainage, burying settlements throughout the western lowlands. The resulting caldera now holds one of South America's most photographed volcanic lakes.

Prior to European contact, major VEI 5 eruptions were produced by Cotopaxi (multiple events from 5820 BCE to 1130 CE), Tungurahua (~1010 BCE), Guagua Pichincha (~930 CE), Cuicocha (~1150 BCE), Pululahua (~690 BCE), Atacazo (~320 BCE and ~2490 BCE), and Soche (~6650 BCE).

The colonial and modern historical record, beginning with Spanish arrival in the 1530s, documents a dramatic concentration of activity. Cotopaxi's eruptions in 1742, 1744, 1768, and 1877 were catastrophic, with the 1877 event generating lahars that reached the Pacific Ocean 100 km away and simultaneously flowed eastward into the Amazon basin — one of the longest lahar run-outs ever documented. Tungurahua's VEI 4 eruptions in 1886 and 1916 devastated the Baños region, while Reventador's VEI 4 eruption in 2002 was the most significant 21st-century eruption on the Ecuadorian mainland, depositing ash on Quito and disrupting air travel across the region.

The 21st century has seen remarkable sustained activity. Tungurahua's 1999–2016 eruptive cycle, Reventador's near-continuous eruptions since 2002, Sangay's ongoing Strombolian activity, and Cotopaxi's reawakening in 2015 have made Ecuador one of the most volcanically active nations in the Western Hemisphere. In the Galápagos, Fernandina erupted in 2017, 2018, 2020, and 2024; Sierra Negra in 2018; and Wolf in 2015 and 2022 — a pace that underscores the vigor of the Galápagos hotspot.

Across the country's entire record, the [[special:volcanic-explosivity-index|VEI distribution]] skews toward moderate eruptions: 39 VEI 0, 25 VEI 1, 121 VEI 2, 58 VEI 3, 29 VEI 4, 14 VEI 5, and 1 VEI 6 event.

Ecuador faces a formidable range of volcanic hazards, compounded by the proximity of major population centers to active volcanoes and the country's extreme topographic relief. Lahars — volcanic mudflows triggered when pyroclastic material mixes with water from glaciers, rivers, or rainfall — represent the single greatest volcanic threat. Cotopaxi's glacier-capped summit can generate lahars capable of reaching the southern suburbs of Quito and the densely populated Latacunga and Los Chillos valleys within 30–45 minutes of onset.

The 1877 Cotopaxi lahars traveled over 100 km and killed an estimated 1,000 people, and modern population growth has dramatically increased exposure. Tungurahua's steep flanks channel lahars directly toward Baños, and Guagua Pichincha threatens Quito's western neighborhoods with both pyroclastic flows and ashfall.

Pyroclastic flows and surges are documented at multiple mainland volcanoes, including Quilotoa, Cotopaxi, Tungurahua, and Guagua Pichincha. Ashfall from explosive eruptions routinely disrupts aviation, agriculture, and urban infrastructure — Reventador's 2002 eruption deposited ash across Quito, disrupting the city for days. Volcanic gases, particularly sulfur dioxide, pose chronic health risks near persistently degassing volcanoes such as Tungurahua and Reventador.

Ecuador's monitoring is coordinated by the Instituto Geofísico of the Escuela Politécnica Nacional ([[ext:https://www.igepn.edu.ec/|IG-EPN]]), which operates seismic networks, GPS stations, gas-monitoring instruments, and lahar-detection systems (acoustic flow monitors) on the country's most dangerous volcanoes. Early-warning systems for lahars are installed in the Cotopaxi drainage and around Tungurahua. Despite these efforts, the combination of densely populated valleys, limited evacuation routes, and the potential for rapid-onset hazards makes Ecuador one of the most volcanically vulnerable nations in the world.

Ecuador's volcanoes are distributed across two geographically distinct regions separated by roughly 1,000 km of Pacific Ocean. The mainland Andean volcanoes occupy the Northern Volcanic Zone (NVZ), stretching approximately 300 km from the Colombian border south to Sangay. Within this zone, volcanoes are arranged in three roughly parallel chains.

The Western Cordillera includes Chimborazo, Quilotoa, Atacazo, and Guagua Pichincha. The Eastern Cordillera (Cordillera Real) contains Cotopaxi, Tungurahua, Antisana, and Cayambe. A third, less prominent back-arc chain to the east includes Reventador, Sumaco, and Pan de Azúcar, erupting chemically distinct lavas.

The Interandean Valley between the two cordilleras, at elevations of 2,500–3,000 m, hosts Ecuador's largest cities — Quito, Ambato, Latacunga, and Riobamba — all situated between active volcanoes.

The Galápagos volcanic province comprises 14 Holocene volcanoes spread across the archipelago. The most active volcanoes (Fernandina, Wolf, Sierra Negra, Cerro Azul) cluster on the youngest western islands of Isabela and Fernandina, closest to the mantle plume. Eastern islands such as San Cristóbal and Santa Cruz are progressively older and less active, consistent with the hotspot track model.

Volcanoes are fundamental to Ecuador's national identity, economy, and cultural heritage. The Avenue of Volcanoes, named by Alexander von Humboldt during his pioneering 1802 expedition (during which he attempted to summit Chimborazo), has become an internationally recognized brand for Ecuadorian tourism. Chimborazo appears on Ecuador's coat of arms, and Cotopaxi, with its perfect glaciated cone, is arguably the most photographed volcano in South America.

Volcanic soils — rich in minerals and nutrients — underpin Ecuador's agricultural productivity, supporting some of the most fertile farmland in the Andes, including the flower-growing industry in the Interandean Valley that makes Ecuador one of the world's largest rose exporters.

Geothermal resources remain largely untapped despite the country's volcanic potential. The Chachimbiro geothermal project in Imbabura province represents early-stage development. Hot springs associated with volcanic activity, particularly those near Baños de Agua Santa at the foot of Tungurahua, are major domestic tourism destinations.

In the Galápagos, volcanic landscapes form the foundation of the islands' UNESCO World Heritage status and a tourism industry generating over $400 million annually. The ongoing eruptions on the Reykjanes Peninsula in Iceland have demonstrated that active volcanism can itself become a tourist draw — a model Ecuador has not yet fully leveraged despite the accessibility of Cotopaxi and Tungurahua's eruptive activity.

Ecuador offers some of the world's most accessible volcano tourism, with several active and glacier-clad peaks reachable within hours of Quito. [[volcano:cotopaxi|Cotopaxi National Park]] receives over 200,000 visitors annually; the standard climb begins from the José Rivas refuge at 4,864 m and summits at 5,911 m, typically requiring 6–8 hours round-trip with crampons and an ice axe. Quilotoa's caldera lake is accessible via a day hike or the multi-day Quilotoa Loop trek through indigenous villages. [[volcano:chimborazo|Chimborazo]], the highest peak in Ecuador, offers a challenging mountaineering ascent from the Whymper or Carrel refuges; clear weather on the summit provides views extending to the Pacific coast.

On the mainland, the Baños–Tungurahua corridor provides dramatic views of the volcano's fumarolic activity (when conditions permit safe access), while Guagua Pichincha's summit crater is reachable via a challenging but non-technical hike from the TelefériQo cable car above Quito. In the Galápagos, Sierra Negra's caldera rim on Isabela Island is one of the most popular volcano hikes in the archipelago, offering views across the 7 × 10.5 km caldera — the largest in the islands. The best time to visit highland volcanoes is during the drier months of June through September, though weather can be unpredictable at altitude.

All visitors to active volcanoes should check current alert levels with [[ext:https://www.igepn.edu.ec/|IG-EPN]] before departure.