QUITO, Ecuador -- A volcano atop one of the Galapagos Islands has erupted for the first time in 33 years, threatening a fragile ecosystem that inspired Charles Darwin's theory of evolution.

Ecuador's Galapagos National Park administration said the 1.7 kilometre-high Wolf volcano began spewing fire, smoke and lava before dawn Monday.

The volcano lies on the northern tip of Isabela Island, the archipelago's largest. It's far from the only population centre, Puerto Villamil, 115 kilometres to the south. Authorities said no tourist activity was affected.

Authorities said lava flowing in the southwest direction for now poses no risk to the world's only population of pink iguanas, which live on the island's northwest tip.