I have been viewing data on Krísuvík volcano and what has been happening recently. Out of this checking I have come to a conclusion that a eruption in Krísuvík volcano is going to place in immanent future. When that might happen is impossible to know for sure.
Far as I know there is no written history on the last eruption at Krísuvík volcano that took place in 14th century. Because of this lack of historic witness of the last eruption in Krísuvík volcano it is impossible to know how the Krísuvík volcano is going to behave before it starts erupting.
It is my un-professional opinion that when a eruption starts in Krísuvík volcano we are going to see something like that took place in Krafla volcano when it erupts. Not exactly like Krafla volcano but something along those lines in eruption style. But Krísuvík volcano is going to have Hawaiian type eruption style when it starts erupting. Unless the eruption takes place under water. Then a Surtseyjan style eruption takes place while a water can get into the crater.
Please note that this is a theory that I am working on. It might work out in part or in full. But then again it might be completely wrong and not work at all. If the second option is true, then I am going to start again and make a new idea on what is going on at Krísuvík volcano.