Eruption of Sierra Negre volcano (23 Oct. 2005):
(free translation of text in image:)
Graphic showing the location of Sierra Negre and the evolution of the eruption of 23 Oct. 2005, published by the newspaper "El Universo". (Free) translation below:
What is nearby? Near the eruption site, the terrain consists mainly of older, unvegetated lava flows. The popoluation of Puerto Villamil is not threatened becaused of its sheltered location at the S of the island. Because of the geologic characteristics (being a typical hot spot volcano, such as Hawaii), the volcanos of the Galapagos Islands produce very fluid lava flows (low viscosity) that permits the flows to travel over great distances.
Evolution of the eruption:
1) The eruption began, at 17:30 h local time on Sunday, 23 Oct. 2005, with a powerful explosion that emptied the uppermost batch of gas-charged magma, heard until 25 km away from the volcano. In addition to the noise of the explosion, a strong smell of sulphur was notised.
2) A gas and ash column rose to about 20 km above the volcano.
3) From a fissure (inferred from photographs), lava fountains started to produce lava flows observed by park rangers. Two flows are travelling towards Elizabeth Bay, while a third one is heading towards Cartago Bay. The lava flows (as on Mon. 24th of Oct.) have reached a distance of 9-10 km.
Backgound: Sierra Negre is the largest of the Galapagos volcanoes, with a caldera 10 km in diameter. Its last eruption occurred in 1979; the lava flows of that eruption did not pose any significant risk to the population of the island.