Is there documentation for this? Icelanders are Christian (since when, I'm not sure), and would more likely pray. Also I don't think there is a history of human sacrifice in Norway/Denmark/Scandinavia.

With the very old tradition I meant the pre christian times (which is why I wrote "the gods").

And I was not necessarily talking about human sacrifice, even though it seems very likely, that this happened as well.

https://scandinaviafacts.com/did-the-vikings-perform-human-s...

Nothing specific to earthquakes and volcanoes or other bad omens, but there was probably some human sacrifice.

https://en.m.wikipedia.org/wiki/Blót

https://en.m.wikipedia.org/wiki/Ättestupa