During the night and last night (20.03.2013) there where two earthquakes on the Reykjanes ridge. Location of this earthquakes is not the same and several hundreds of km between them. So they are in fact not connected at all. This is just by chance this activity takes place at the same time. As often is the case in this type of area.
The first earthquake was an magnitude 5.4 earthquake deep on the Reykjanes ridge. This earthquake was on 10 km, or at least that is the best estimate by EMSC. The distance from Reykjavík is about 1100 km. More information on this earthquake can be found here on EMSC web site.
The second earthquake was an magnitude 4.3 earthquake, with the default depth of 10 km according to GFZ. It had the distance about 850 km from Reykjavík. More information on this earthquake can be found here on EMSC web site.
It is impossible as before to know what is happening on at this location. Due to the depth of the ocean at this place and how remote this location is.