Seismic tremors ten kilometres beneath Eyjafjallajökull, west of Mýrdalsjökull, indicate that an eruption of the volcano Katla may be in the near future, due to its proximity to the glacier. Similar tremors more than a decade ago caused magma intrusions beneath Eyjafjallajökull. Activity below Eyjafjallajökull last caused an eruption of Katla in 1823, after two years of tremors and palpitations.
Considered to be one of the most dangerous volcanoes in Iceland, Katla last erupted in 1918 and there have been fifteen other documented eruptions dating back to the year 930. Katla typically erupts every 40-80 years.