What you are seeing in these images and the next video is a rash different from the others. The blue dye surrounding the lava comes from the flames produced by sulfuric gases.
The volcano contains large amounts of pure sulfur, which emits a violet color when burning, filling the air with toxic fumes. The image above was taken on an erupting volcano in Ethiopia.
French photographer Olivier Grunewald He has specialized in this kind of images, which he takes without using filters or image modifications. To get it, you have to wait until nightfall, when the blue flames are visible. Work with a gas mask to avoid breathing toxic fumes.
It is not the first time that Grunewald travels the world to take images of blue lava. In January, he traveled to Indonesia to photograph the volcano Kawah Ijen. The volcano is the subject of a new documentary produced by Grunewald and Régis Etienne, the president of the Geneva Volcanology Society, which was released earlier this year.