A volcano on the largest of the Galapagos Islands has begun erupting and authorities are evaluating possible dangers to the island's famed plant and animal life, officials said Friday.

Rangers and tour guides spotted lava flowing down the northeastern flank of the Cerro Azul volcano on the seahorse-shaped island of Isabela late Thursday, the Galapagos National Park said in a statement.

Ecuador's Geophysics Institute said that satellite data and a flyover of the island by park officials showed a "small amount of ash" coming out of the volcano, located on the southwestern edge of the island.

The eruption is not endangering people on the island, park official Vinicio Pauta said.

The 5,600-foot Cerro Azul — one of five active volcanoes on the island — last erupted in September 1998, causing minor damage to plant life. Cerro Azul is located in the unpopulated southwestern corner of the island.

The Galapagos Islands, 625 miles off of Ecuador's Pacific coast, are known for unique plant and animal life, including giant tortoises, marine iguanas and seabirds known as blue-footed boobies. Charles Darwin's observations of the islands' finches helped inspire his theory of evolution.