Azufral VulkanAzufral volcano (Azufral de Túquerres) is a stratovolcano in southern Colombia with a 2.5x3 km wide caldera 35 km SW of Galeras volcano. The last eruption took place about 1000 years ago.
Beschreibung:Azufral's caldera contains a complex of several Holocene rhyodacitic lava-domes.
The crescent-shaped Laguna Verde lake occupies the NW side of the caldera. Laguna Verde is an acid lake (pH 2.4)) with hot springs on the NE shore of the lake (temperatures of 54°C, pH of 2.6, measured in 1990).
The latest lava dome in the caldera was formed about 3600 years ago and still has active fumaroles.
Azufral volcano's lavas contain more silica than the nearby volcanoes and rhyolitic-dacitic tephra deposits from explosive activity mantle the volcano.
1971 seismic swarm
Between 26 April and 7 May 1971, a swarm with more than 60 earthquakes under the volcano were felt by residents of Santander village. Some of the quakes were even detected by seismographs at Pasto seismic station 215 km from the volcano (Galeras volcano observatory).