Today (30-September-2020) Icelandic Met Office moved Grímsfjall volcano to a yellow warning status for air traffic. This strongly suggests that Icelandic Met Office thinks that an eruption might happen in next few days to weeks. It is expected that an eruption might happen if a glacier flood happens from Grímsvötn glacier lake that is inside Grímsfjall volcano caldera.
It is difficult to know if this is going to be a large or small eruption until it happens. Best thing to do right now is to keep monitoring Grímsfjall volcano activity to see if anything is going on. Currently everything is quiet.
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