Nisyros Geopark

Stefanos Crater
Stefanos Crater

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 be a result of two major NE trending active faults marked by an alignment of fumarolic vents. Its age is also unknown. 7 stratigraphic layers have been identified on the eastern walls of Stefanos, where they are best exposed. From bottom to top, they include talus of magmatic lithics, epiclastics and fine argillitic layers, fine grained lacustrine deposits, compact deposits of the eruption products that formed the Kaminakia craters, deposits from the eruption of Stefanos itself as well as a thin layer of explosive products from Polyvotis.

Stefanos Crater
Stefanos Crater
Stefanos Crater
Stefanos Crater
Fumaroles
Fumaroles
Hot steam at Stefanos Crater
Hot steam at Stefanos Crater
Stefanos Crater
Stefanos Crater
Stefanos Crater
Stefanos Crater
Debris inside Stefanos Crater
Debris inside Stefanos Crater

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Geosites

Mikros Polyvotis Crater

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 […]
Lava Flow

Lava Flow

During the early stages of the Composite Stratovolcano cycles, a series of eruptive events took place that marked the transition from the earliest shield volcano to stratovolcano. This period of […]
Nikia Rhyolites

Nikia Rhyolite

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 […]
Kateros Rhyodacitic Lavas

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 […]
Lakki Steam

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 […]
View of Lakki Hydrothermal Craters

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 […]
Pergousa Islet (Right)

Pergousa Islet

Pergousa is a volcanic islet that consists of weathered thick lava flows and domes of andesitic to dacitic composition, which are covered by pumice deposits of KPT from nearby Kos […]
Scoria

Basaltic – Andesitic Lava Flows covered by Scoria

During the Composite Stratovolcano eruptive cycle, lavas and pyroclastic deposits from the growing cone occur throughout the island, typically in lateral cones. They include remnants of cinder, spatter and scoria […]
Megalos Polyvotis Crater

Megalos Polyvotis Crater

Megalos Polyvotis resulted from the early and strongest hydrothermal explosive cycle of the Lofos area. It is an elliptical (180x350m) crater and its 3–5 m thick ejecta are partly covered […]
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. […]
View of Stefanos Crater

View of Stefanos Crater

Impressive view of Stefanos from the area of Kaminakia, two crescent shaped hydrothermal craters at the SE walls of the caldera. Stefanos Crater is one of the largest phreatic craters […]
Pumice

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 […]
Parletia Rhyolitic Lava Neck

Parletia Rhyolitic Lava Neck

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 […]
View of Strongyli Crater

Strongyli Crater

Strongyli islet is a volcanic cone, located at the north of Nisyros. It is built from approximately 675m of depth up to 128m of altitude with an overall volcanic relief […]
Andesitic Pyroclastic Sequence

Andesitic Pyroclastic Sequence

Along the road that leads to Lakki, within the inner Northeastern caldera rim, one can enjoy a fascinating volcanological sequence. During the Early Shield Volcano eruptive cycle, three characteristic eruptive […]
View of Rhyodacites

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

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 […]
Volcanic Observatory

Volcanic Observatory

This vantage offers splendid view of the flat area of the caldera (Lakki Plain) with the characteristic Stefanos crater, along with the hill that hosts the post caldera craters of […]
Andreas Crater

Andreas Crater

Andreas is a small circular crater, which is also called Mikros Stefanos Crater and it is located at the southwest rim of Stefanos crater. The Stefanos deposits are unconformably ovelied […]
Panoramic View of the Craters

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 […]
Pachia Islet (Center)

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 […]
Basaltic Andesitic Lava Neck

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 […]
Pillow Lavas at Mandraki

Pillow Lavas

The NE coast of Nisyros is dominated by basaltic andesitic pillow lavas, that were emitted during the ‘Submarine Volcanic Base’ eruptive cycle, the first volcanic activity that took place at […]
Interactive Map