Furnas Volcano | John Seach


Sao Miguel Island, Azores

37.77 N, 25.32 W
summit elevation 805 m

Furnas volcano is located on the eastern end of Sao Miguel Island. The volcano contains two calderas. The youngest caldera is 5 km in diameter and located within an older less distinct caldera 7 X 5 km in diameter. Over 3000 people live in the caldera.

Pico do Gaspar lava dome is located east of the Lagoa das Furnas caldera lake. Two historical eruptions have occurred at Furnas, 1441 and 1630. At least ten explosive eruptions have occurred at Furnas volcano in the last 5000 years.

2013 Earthquake
A magnitude 5.8 earthquake hit 32 km SE of Furnas volcano on 30th April 2013. The focus was at a depth of 10km.

1630 Eruption
On 2nd September 1630 a series of earthquakes lasted for 6 hours followed by a magmatic eruption from the southern part of the caldera. Reports described “a mountain rising through the air” and “clouds of fire from two of the lakes” and “fire in the sky that lit the whole island”. Between 80 and 115 people (half the population of the village) were killed in Ponta Garca by pyroclastic flows. Eruptions fluctuated between magmatic and phreatomagmatic activity for most of the explosive phase which lasted 3 days. Ash fell as far as Corvo 550 km to the west-northwest. Lava dome growth began after the explosive phase.

Further reading
Guest et al., 2015. The volcanic history of Furnas Volcano, São Miguel, Azores. Geological Society, London, Memoirs44(1), pp.125-134.

Guest et al, 1999. Volcanic geology of Furnas Volcano, São Miguel, Azores. Journal of Volcanology and Geothermal Research92(1-2), pp.1-29.

Furnas Volcano Eruptions

1630, 1441 ± 2, 1430 ± 100, 1170 ± 100, 840 AD ± 100, 80 AD ± 100, 360 BC ± 150, 1670 BC ± 1000, 4570 BC.