The second occurred last night around 2 am and measured 3.4. 

 Yesterday afternoon an earthquake of 3.9 was detected at Grímsey followed by two more earthquakes last night at 3.5 and 3 consequently.  noncleared-maintext”>
Several earthquakes were measured at Grímsey island north of Iceland last night as well as at Bárðarbunga but according to the Iceland Met Office there is no sign of volcanic unrest. 
Two earthquakes at a magnitude of over 3 were measured at Bárðarbunga in the last 24 hours. The earlier one occurred yesterday morning just before 10 am and measured 3.7.