[9] The caldera of the Katla volcano has a diameter of 10 km (6 mi) and is covered with 200–700 metres (660–2,300 ft) of ice.

The name Katla derives from the word ketill ("kettle"), referring to the form of the volcano.

[3] The 1918 eruption resulted in extending the southern coast by 4 km (2.5 mi) due to laharic flood deposits.

[15] Apart from the 1755 and 1918 eruptions already mentioned in this regard, both of which like the majority of large floods drained onto the Mýrdalssandur plain to the volcanoes south-east, an eruption in 822 drained from the north-east aspect of the caldera down the Markarfljót river flood plain to the mountain's south-west covering an area of 600 km2 (230 sq mi).

[15] Before the Hringvegur (Iceland's Ring Road) was constructed in 1974, people feared traversing the plains in front of the volcano because of the frequent jökulhlaup (or glacier bursts) and the deep river crossings.

On 9 October 2010, a sudden rise in harmonic tremor was observed in the stations around Katla, but although a sign of a possible impending eruption,[24] none occurred.

A few days later, an earthquake swarm took place in the caldera, indicating magma movement inside the volcano, leading to increased fears of an eruption in the near future.

[28] Scientists monitoring the activity said speculation that it was caused by a "very small" subglacial eruption lacked confirmation by visual or seismic evidence.

[31] An update written at 11 Sep 16:38 GMT reported:Today, shortly before 14:00, a small earthquake swarm began in Mýrdalsjökull.

[39] These are often manifest as depressions in the ice cap rather than full thickness to the underlying rock cauldrons and have variable activity.

[15]: 74 [42] It is most likely to occur in the months June to September, and be associated with a jökulhlaup flowing from Kotlujökull an outlet glacier to the south-east, over Mýrdalssandur to the sea where it could affect the town of Vík í Mýrdal.

The Icelandic Meteorological Office updates its website with reports of quakes both at Eyjafjallajökull and Katla.

[46] The folktale recorded by Jón Árnason in 1862[47] probably dates much older since it is set in the time of the Þykkvabæjarklaustur [is], the Catholic monastery abolished c.

[48] The short folktale entitled "Katla eða Kötlugjá" can be summarized as follows: In the pre-Reformation days when the Þykkvibær monastery was installed with an abbot, they had a cranky housekeeper there named Katla, well versed in (ancient) magic (fjölkynngi), instilling fear in others.

[48] She owned a magical pair of breeches (brók, 'trousers'), which allowed its wearer to run endlessly without fatigue, but herself reserved its use for an emergency.

One day in autumn, the abbot's shepherd Barði has trouble rounding up the sheep before master and the housekeep return from a banquet, and he borrows the breeches to retrieve the stray.

[49] But as winter wore on, the whey began to dwindle and Katla was heard muttering "Barði will soon appear".

[50] Realizing the discovery of her crime and punishment was imminent, she put on her breeches and disappeared to the northwest, presumably diving straight into the glacier.