5
$\begingroup$

I was studying a satellite map of Iceland and came across an interesting, but unnamed feature located between Vatnajökull glacier and Trölladyngja volcano (between 64°50'35"N, 17°11'21"W and 64°48'33"N, 17°04'25"W ; link to google maps). It is a distinct, bright patch of land, around 6.5km across with an indentation in the center. Its color and texture are different than these of the lava field next to it and the indentation looks (to my untrained eye) more like a collapsed lava bubble than a caldera.

Is it a volcano or something else?

enter image description here

| improve this question | | | | |
$\endgroup$
  • $\begingroup$ @Fred are you sure that attaching this picture is OK? I was considering doing the same, but it seems that cannot be used without permission: law.stackexchange.com/questions/37291/… $\endgroup$ – robaki Mar 12 at 17:50
  • $\begingroup$ The question you reference discusses the commercial use of images. $\endgroup$ – user2448131 Mar 13 at 1:14
  • 1
    $\begingroup$ In addition to what @user2448131: states, there's a 2020 Google watermark on the picture to prevent commercial usage $\endgroup$ – Fred Mar 13 at 5:01
6
$\begingroup$

The place is called Urðarháls. I could not find much information about it in the scientific literature... It is mentioned in Sigmarsson & Halldórsson (2015): they say it's an interglacial basaltic shield volcano, possibly associated with the Askja volcanic system. The fact that the volcano was eroded by glaciers probably explains the colour difference with the surrounding "fresh", postglacial lavas.

The crater looks like a pit crater to me: it probably collapsed when lava was drained somewhere else, leaving an empty chamber beneath it. Another good example of pit crater is the Dolomieu, on Piton de la Fournaise, which collapsed in 2007. Look at Staudacher et al. (2009): compare figure 3, before the collapse, and figure 11, after.

Note that the authors use the term "caldera", which is loosely defined... What Wikipedia calls a non-explosive caldera would be referred to as a pit crater by some. I guess the two terms kind of overlap.

| improve this answer | | | | |
$\endgroup$
  • 1
    $\begingroup$ nice, thanks for the literature pointers and pointing out the caldera-crater issue $\endgroup$ – robaki Mar 11 at 16:29
3
$\begingroup$

According to this geological map of iceland it is the Urðarháls, an interglacial shield, i.e. a dolomite shield volcano that got scraped by glacial activity The hole in the middle is the pit crater. You can find some cool pictures of it if you google the name with the correct icelandic letters.

| improve this answer | | | | |
$\endgroup$
  • $\begingroup$ I've found this "dolomite" volcano information somewhere on the web, but it must be a mistranslation: dolomite is a sedimentary carbonate rock, I doubt it can be erupted from a volcano, even at Ol Doinyo Lengai! :) $\endgroup$ – Jean-Marie Prival Mar 11 at 10:12
  • $\begingroup$ @Jean-Marie Prival You are obviously correct! $\endgroup$ – R.K. Mar 11 at 10:27
  • $\begingroup$ thanks for your answer! The geological map doesn't seem to work with my browser - which one do you use? $\endgroup$ – robaki Mar 11 at 16:19
  • $\begingroup$ For me, it works with Chrome, Firefox or Edge. The original link for the "Geological Web Map" comes from this page: en.isor.is/geological-maps-geological-web-map $\endgroup$ – R.K. Mar 11 at 16:32
  • $\begingroup$ thanks, I use Firefox too, and turning off addons didn't help. Well, this is not a problem for this site anyway. Thanks again for your answer, the Urðarháls pictures are cool indeed! $\endgroup$ – robaki Mar 11 at 17:47

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.