Flegethron

Flegethron

The large elliptical-shaped Flegethron (or Alexandros) crater occupies the southeastern part of the area, intersecting with Megalos Polyvotis.

Towards the southwest, the crater collapsed and filled with its own debris. The history of this hydrothermal crater goes back to 1971, when the first recorded hydrothermal eruption took place within the western part of Lakki and as a result, gave birth to Polyvotis and Flegethron. The activity continued during 1973, accompanied by steam effusion, loud explosions and lithic ejecta from the Lofos Rhyodacitic dome, without any signs of magmatic activity. The floor of the southern part is covered with lacustrine sediments.

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Geosites

Volcanic Observatory

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Pachia Islet

Pachia is a volcanic islet to the west of Nisyros. It features basal dacitic lavas overlain by two pumice sequences of the Kos Plateau Tuff unit that, as its name […]

View of Lakki Hydrothermal Craters

Panoramic view of the flat part of the caldera (Lakki). Visible is the rhyodacitic hill that hosts the hydrothermal craters (Alexander, Mikros and Megalos Polyvotis and Logothetis). In the middle […]

View of Rhyodacites of Prophytis Ilias

View from the west of the Rhyodacitic Domes of the Caldera, the youngest lava intrusions during the last magmatic phase, the ‘Post-Caldera Eruptive Cycle’. The post-caldera rhyodacitic lava domes comprise […]

View of Lava Terraces

During the Caldera Forming eruptive cycle, two significant and violent plinian-type eruptive events took place at Nisyros. Between these events, there was a first caldera that formed after the first […]

Panoramic View of the Craters

Breathtaking view of the hydrothermal craters of Nisyros. To the left are Mikros (Andreas) and Megalos Stefanos and to the right the rhyodacitic hill that hosts the post caldera craters […]

Pumice

Cape Katsouni, located at the northern coast of the island, hosts impressive geological formations from two of Nisyros’ most iconic eruptive cycles. The bottom formations consist of a basaltic andesitic […]

Kateros Rhyodacitic Lavas

During the Post-Caldera eruptive cycle, the last magmatic activity that took place in Nisyros up to 15000 years ago, huge amounts of lavas of rhyodacitic composition were emitted following the […]

Stefanos Crater

The elliptical Stefanos Crater is one of the largest phreatic craters in the world, with dimensions of 260x350m. It has a maximum depth of 27m and its shape seems to […]

Basaltic – Andesitic Lava Neck

Characteristic neck of basaltic andesitic lavas at Kato Lakki. Volcanic features like this are pipe-like masses of lava, agglomerates and breccias the fill former conduits of lava through which it […]

Volcano View

This vantage offers splendid view of the flat area of the caldera (which is called Lakki) with the characteristic Stefanos crater, along with the hill that hosts the post caldera […]

Mikros Polyvotis Crater

The Mikros Polyvotis crater with a floor diameter of 30m is the youngest hydrothermal crater of the Lofos area. Intersects the eastern rim of Megalos Polyvotis, and occurred as a […]

Andreas Crater

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Pergousa Islet

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Andesitic Pyroclastic Sequence

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View of Stefanos Crater

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Nikia Rhyolite

Lava Flow

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Megalos Polyvotis Crater

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Parletia Rhyolitic Lava Neck

Pillow Lavas

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Strongyli Crater

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Basaltic – Andesitic Lava Flows covered by Scoria

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Interactive Map

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