Caldera of Sierra Negra on Isabela Island

February 05, 2019

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Photographer: Gabrielle Tepp 
Summary Author: Gabrielle Tepp 

The white clouds at ground level on the photo above result from fumaroles on Isabela Island, (Galapagos Islands, Ecuador). Fumaroles, consisting of hot gases including water vapor and sulfur dioxide, can be dangerous to those who wander too close. The ones featured here are found within the caldera of Sierra Negra (3,688 ft or 1,124 m), the largest of the active volcanoes in the Galapagos Islands. Note that the yellow deposits near the base of the fumaroles are sulfur. This area was formerly mined for sulfur, giving it its name: Minas de Azufre (Spanish for Mines of Sulfur).

When this photo was taken, on April 22, 2018, Sierra Negra was undergoing a period of ground inflation that ended in a minor eruption two months later. However, hydrothermal activity and passive, non-explosive gas release are normal behavior for many active volcanoes and are not necessarily a sign of an impending major eruption.

Photo Details: Camera: Canon EOS REBEL T5i; Software: Windows Photo Editor 10; Exposure Time: 0.0040s (1/250); Aperture: ƒ/9.0; ISO equivalent: 100; Focal Length: 61.0mm; Lens: 18-250mm.