The glacier Mýrdalsjökull is the 4th largest glacier in Iceland, 1480 m and around 701 km2.
Above Höfðabrekkujökull and under Mýrdalsjökull is the volcano Katla which has erupted 16 times in the last 1100 years. About once every 70 years or so. The last eruption was in 1918 and the first one was around 894