Pseudocraters near Myvatn, Iceland
Tuesday, August 16, 2011 4:22:43 PM
Pseudocraters are formed by steam explosions as flowing hot lava crosses over a wet surface, such as a swamp, a lake, or a pond. The explosive gases break through the lava surface in a manner similar to a true volcanic eruption, and the tephra builds up crater-like forms which can appear very similar to real volcanic craters.
Well known examples are found in Iceland like the craters shown here at lake Mývatn (Skútustaðagígar).
The name of Mývatn (Icelandic mý ("midge") and vatn ("lake"); the lake of midges) comes from the huge numbers of midges found there in the summer. We were lucky this summer not to be disturbed by midges, but that is of course bad news for the local fisheries. The bottom part of pseudocraters is a favoured whereabouts for midges, and thus also a place where many of them die and fertilise the place. Therefore the bottom of the pseudocrater is much greener.