EGU24 Photo Competition finalists – who will you vote for?

The 2021 Fagradalsfjall volcanic eruption was the first one in the area after approximately 800 years. The photo captures the fire-fountaining phase of this eruption, during which geochemistry and petrology studies show that magma was flushed out from the base of the crust to the surface, thanks to a direct connection with the deep reservoir. During this phase, the volcano emitted high fountains of lava and tephra material, showering the vicinity of the crater.

This image is called ‘The Concert’. Agate is made of microcrystalline fibrous quartz, called chalcedony, and provides eye-catching photomicrographs because of the fine layering and radial textures it often displays. I had this thin section made from a small agate slab collected at a friend’s shop. I was attracted by the unusual look for an agate: a milky white diaphanous banding and a top layer of purple amethyst. A real beauty!

Under the microscope, an extremely fine-grained, unique texture came out from the milky layers of this agate, which is one of my most photogenic rocks. We can appreciate the fine grain-size in the central and top parts of the photo, as opposed to the coarser crystals in the lower band. In the latter, the parallel vertical alignment of some crystals recalls a crowd facing a stage (The Concert) or a beach. The grain size of the chalcedony crystals – about 10 µm – makes this specimen particularly challenging in terms of focus, because light passes through an aggregate with more grains on top of each other, that create an unavoidable blurry effect. Width of view: 5,3 mm.

Las Grietas, a fascinating geological feature on Lanzarote, owes its origin to volcanic activity. Located between Tias and San Bartolomé, these narrow cracks in the cliff-side formed when the volcanic plates of Montaña Blanca fractured and cooled gradually. Walking through Las Grietas feels like strolling through a miniature version of famous canyons like Antelope Canyon in Arizona or the Grand Canyon.

Keshit village in Kerman province, Iran, which looks a lot like a tree in satellite images.

The Reynisdrangar basalt stacks rise dramatically out of the sea in front of the black volcanic sands of Reynisfjara beach, below Reynisfjall, a 340 m high tuff mountain formed by a volcanic eruption under a glacier in the penultimate ice age near the village of Vik, Iceland. The Reynisdrangar stacks are a collection of 66m high rocks from the same geological formation as Reynisfjall. Legend has it that the stacks were created when two trolls dragged a three-masted ship ashore unsuccessfully, and when daylight broke they became needles of rock.

Observe the flow of the river Unica that comes out of the darkness.

The early morning sun highlights the topography at the Viti crater, situated next to the Öskjuvatn Lake, Iceland. Geologists measured ground displacement by flying a drone over the lake shores every few years and comparing the changes between successive 3D surface models. We see here a detail of the 2023 orthophoto, generated with >11’000 photos of a Wingtra One GenII drone. While the Viti crater was formed in 1875 and contains acidic (pH 2) and warm (28°C) water, the Öskjuvatn Lake is neutral and cold, explaining the colour change. The Viti crater is about 190 m in diameter for scale.