It has just been announced in the news that Grímsvant glacier lake has just had an glacier flood, but this lake is in the Grímsfjall volcano caldera. This glacier flood is believed to have started yesterday around 12:00 UTC. The glacier river that the water is running into is called Gígukvísl. So far this appears to be minor flood so far. But I do not know how much water as in Grímsvatn lake when this flood did take place.
At current time it is impossible to know if an eruption is going to take place following this glacier flood from Grímsvatn lake in Grímsfjall volcano.
I am going to post more information about this as I get them.
Icelandic news about this. Use Google Translate if you want to get incomprehensible news about this event.