pseudocrater

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The Pseudocraters of Iceland:

A pseudocrater looks like a true volcanic crater, but is not. These distinctive landforms are created when flowing hot lava crosses over a wet surface, such as a swamp, a lake, or a pond causing an explosion of steam through the lava. The explosive gases break through the lava surface in a manner similar to a phreatic eruption, and flying debris builds up crater-like feature which can appear very similar to real volcanic craters. Pseudocraters are also known as rootless cones, since they are characterized by the absence of any magma conduit which connects below the surface of the earth.

A classic locality for pseudocraters is the Lake Myvatn area of northern Iceland that was formed 2,300 years ago by basaltic lava eruption. The lava flowed down the Laxárdalur Valley to the lowland plain of Aðaldalur where it entered the Arctic Ocean about 50 km away from Mývatn. There was a large lake in the area at the time, a precursor of the present-day Mývatn. When the glowing lava encountered the lake some of the water-logged lake sediment was trapped underneath it. The ensuing steam explosions tore the lava into small pieces which were thrown up into the air, together with some of the lake.

By repeated explosions in a number of locations, groups of craters built up and now dominate the landscape on the shore of Lake Mývatn and also form some of the islands in the lake. The Myvatn pseudocraters occur in several groups around the lake and as islands within the lake. A group of such craters at Skútustaðir on the south shore of the lake is protected as a natural monument and is frequented by tourists. Other pseudocrater groups in this lava field are in the Laxárdalur Valley and Alftaver district. Pseudocraters have also been discovered in the Athabasca Valles region of Mars, where lava flows superheated groundwater in the underlying rocks.

Pseudo crater / Pseudokráter – Myvatn lake, Northern Iceland

Imagine the power of the steam explosion that created these pseudo craters when hot lava reached the lake. Taken during HEAVY rain, I was sokaing wet and the camera too :)

Představte si tu sílu výbuchu páry, která vytvořila tyhle pseudokrátery, když horká láva dosáhla až k jezeru. Foceno během velkého lijáku, byl jsem mokrej skrz na skrz a foťák taky :)

Những chiếc hố rỗng lạ lùng trong hồ cổ Iceland

Những chiếc hố rỗng lạ lùng trong hồ cổ Iceland

Những chiếc hố rỗng lạ lùng trong hồ cổ Iceland.

Quang cảnh hiện tại là kết quả của những vụ phun trào núi lửa dữ dội diễn ra hàng ngàn năm trước. Trong hồ sinh ra hơn 50 hòn đảo nhỏ gọi là Pseudocraters, nhìn vào giống hố rỗng.

Khi nhìn vào Pseudocrater, nó trông giống như một miệng núi lửa thật sự, nhưng trong thực tế thì không phải. Những địa hình đặc biệt này được tạo ra khi dung nham nóng…

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Lake, Grass and the Pseudocraters – Lake Myvatn, Northern Iceland

Jezero, tráva a pseudokrátery  – Jezero Mývatn, Severní Island 

Tohle jsem vyfotil během tůry kolem jezera Mývatn. Kusy lávy, které vidíte poblíž, byly vytvořeny tím, že láva přitekla do oblasti, začala tavit kameny a neměla kudy odtéct. Následně se potom hráz protrhla, láva odtekla a kameny zůstaly. Uprostřed jezera můžete vidět pseudokrátery vytvořené obrovskými explozemi páry, když láva přitekla do jezera.

I took this during a hike around lake Myvatn. The chunks of lava you can see nearby were created by a pool of lava that was unable to escape the area and was slowly melting rocks from a different material. When lava finally escaped the rocks remained. In the middle of the lake you can also see some pseudo craters created by huge explosions of steam when lava reached the lake.

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