[2] Seismic activity surrounding the Bárðarbunga volcano gradually increased from 2007 to 2014, with a brief pause during the nearby eruption at Grímsvötn in 2011.

There were "very strong indications of ongoing magma movement, in connection with dyke intrusion" according to the Icelandic Meteorological Office.

[3] On 23 August an intense low-frequency signal was detected which led scientists to believe that a small eruption was in progress under the Dyngjujökull glacier.

As a result of this the Aviation Color Code was elevated to a maximum Red, signifying that an eruption was either imminent or in progress and that a no-fly zone was in effect for planes to the south-east of Iceland.

It was stated that 700 earthquakes of larger magnitudes than previously recorded had been observed since midnight; the dyke stretching to the north was estimated at 30 km in length; activity showed no signs of abating and an imminent eruption was considered possible; the intense low frequency signal detected on 23 August was not caused by a sub-glacial eruption.

A M4.5 event was recorded just east of the Askja caldera, which had been showing signs of increased geothermal activity since April 2012.

At 20:50, scientists on a surveillance flight reported a 4–6 km line of 10–15 m deep cauldrons to the south of the Bárðarbunga caldera, which were possibly a result of melting or a sub glacial eruption, although they didn't know when they had formed.

[5] The fissure eruption breached the surface between Bárðarbunga and Askja, close to the northernmost point of the earthquake swarm, in the Holuhraun lava field 42 km to the northeast of the caldera.

GPS measurements showed continuing changes to the north of the eruption, seismic activity had decreased but was otherwise similar to previous days.

A white plume rose from the eruption reaching 15,000 feet and extending 60 km NNE; no ash but high levels of sulphur dioxide were recorded.

[3] On 6 September, radar measurements of the glacier surface within the caldera showed 15 metres of subsidence, a volume change of 0.25 square kilometres.

[9] On 9 and 10 September, earthquakes continued to be recorded at Bárðarbunga caldera with a M5.5 at 05:28 on the 10th in the northern part of the dyke intrusion, and also at Herðubreiðatögl [ˈhɛrðʏˌpreiːðaˌtʰœkl̥].

Continued sulphur dioxide emissions at the eruption sites prompted concerns about air quality in urban areas in eastern Iceland.

Forecast scenarios now included references to possible further subsidence in the caldera prompting eruptions beneath the Dyngjujökull glacier.

[3] By 21 September, subsidence in the caldera, as measured at the newly mounted GPS station, was approximately 40 cm per day and appeared to coincide with earthquake activity.

Geothermal heat was on the increase and the depression in the caldera was 40 metres, subsidence continued at a similar rate to previous weeks.

A cauldron in the south-east corner of Bárðarbunga deepened 25 metres in one month and was considered by scientists at the site to be linked to the depression in the caldera.

The eruption continued to emit intense sulphurous gasses which affected air quality throughout Iceland, depending on the weather conditions.

On 25 December, a new earthquake sequence was recorded at the Geysir geothermal field 140 kilometres west of Bárðarbunga; the activity lasted for two days before fading out.

[3] A scientific report published on 30 January featuring graphs and diagrams showing detailed information about the caldera seismicity and eruption can be found on the IMO website.

The rate of subsidence of the caldera was slower at about 5 cm per day and levels of toxic gasses in inhabited areas stayed within safety limits for consistent periods.

[14] Nevertheless, air pollution continued, and the area north of Bárðarbunga, including volcanoes Askja and Herðubreið, still remained closed to visitors.