Sierra Negra: A Deep Dive into a Galapagos Shield Volcano
Sierra Negra, on Isabela Island in the Galapagos, is one of the most active volcanoes of this famous archipelago and the site of one of the largest volcanic calderas in the world. A broad basaltic shield volcano born of a hotspot in the Pacific, it is part of the volcanic landscape that shaped the unique wildlife Charles Darwin encountered, and which still makes the Galapagos a living laboratory of evolution.
A vast Galapagos shield
Sierra Negra reaches about 1,124 metres and is a broad shield volcano on Isabela, the largest island in the Galapagos. Like the Hawaiian volcanoes, it is built from fluid basaltic lava erupted over a hotspot, giving it gently sloping flanks and a wide profile. Its summit is crowned by an enormous caldera, one of the largest of any volcano on Earth.
One of the world's largest calderas
The caldera of Sierra Negra is remarkable for its sheer size, a broad, shallow basin several kilometres across formed by the collapse of the summit as magma drained from below. This vast caldera is a defining feature of the volcano and a striking example of how shield volcanoes can develop large summit depressions through repeated drainage of their magma reservoirs.
A hotspot volcano
The Galapagos Islands sit above a volcanic hotspot in the Pacific Ocean, where a plume of hot mantle material feeds the volcanism that built the archipelago. Sierra Negra is one of several active shield volcanoes on Isabela, the youngest and most volcanically active part of the Galapagos, where the hotspot currently lies. The islands grow older and more eroded toward the east, away from the hotspot.
Frequent eruptions
Sierra Negra is one of the most active volcanoes in the Galapagos, with eruptions recorded over the past two centuries, including significant activity in recent years. Its eruptions typically produce fluid lava flows from fissures on its flanks and within the caldera, adding fresh basalt to the island. This activity is closely watched, both for science and for the protection of the Galapagos environment.
A laboratory of evolution
The Galapagos Islands are famous as the place where Charles Darwin made observations that helped lead to the theory of evolution by natural selection. The volcanic origin of the islands, their isolation, and their distinct environments allowed unique species to evolve. Sierra Negra and the other volcanoes are the geological foundation of this living laboratory, where evolution can still be observed today.
Unique wildlife on volcanic land
The slopes and surroundings of Sierra Negra are home to remarkable Galapagos wildlife, including giant tortoises and other species found nowhere else. The volcanic soils and varied habitats created by the island's volcanism support this exceptional biodiversity, a key reason the Galapagos are protected as a national park and a UNESCO World Heritage Site.
Monitoring and protection
Ecuador monitors the volcanoes of the Galapagos, including Sierra Negra, both to understand their activity and to protect the archipelago's unique ecosystems. Managing volcanic activity in such an ecologically sensitive and protected environment presents a distinctive challenge, balancing scientific study with the conservation of one of the world's most precious natural sites.
Explore on the map
Sierra Negra stands among the volcanoes of the Galapagos Islands, alongside Wolf, Cerro Azul, and others on Isabela and neighbouring islands. Explore it on the interactive map — filter by country to see Sierra Negra among Ecuador's volcanoes and to appreciate the volcanism that built this extraordinary archipelago.