The Krysuvik geothermal area near Reykjavik

The Icelandic Meteorological Office said the quake struck at 1.43pm today and was centred near Krysuvik, about 20 miles south of the capital (Pictured: The Krysuvik geothermal area near Reykjavik)
Iceland's capital Reykjavik has been rattled by a 5.6-magnitude earthquake a week after rumblings were detected at the volcano which grounded 900 flights in 2011.

The Icelandic Meteorological Office said the quake struck at 1.43pm on Tuesday and was centred near Krysuvik, about 20 miles south of the capital. There were no immediate reports of injuries.

Prime Minister Katrin Jakobsdottir was being interviewed on live television from her home when everything around her started shaking.

'Oh my God there's an earthquake,' she said as she grabbed hold of the desk in front of her and gasped.

'Well this is Iceland!' The 44-year-old PM said as she laughed off the bang, saying she was 'perfectly fine' and 'the house was still strong.'

Meanwhile, the parliament in Reykjavik was also rocked by the seismic movements, sending an MP addressing the house rushing for cover.

Helgi Hrafn Gunnarsson, MP for the Pirate Party, scarpered away from the lectern while the Speaker, Steingrímur J. Sigfússon, stayed seated behind him.

'Just sit calmly, sit calmly,' the elder statesman is heard telling the MP.

It comes after scientists last week warned that the Grímsvötn volcano was gearing up for another eruption.

The volcano is notorious for spewing a 12-mile ash cloud into the air and causing the cancellation of 900 flights in 2011.

Another Icelandic volcano, Eyjafjallajökull, erupted in 2010 and this caused far more unrest, grounding around 100,000 flights.

This is despite Eyjafjallajökull being considerably smaller than Grímsvötn.

Scientists have recorded signs of unrest in the area, with seismic activity indicating magma is swelling in the plumbing of the volcano.

Dr Dave McGarvie, a volcano expert at Lancaster University, adds in an article for The Conversation: 'Increasing thermal activity has been melting more ice and there has also been a recent increase in earthquake activity.'

All these signs point to an imminent eruption and the next signal which experts are watching for is 'an intense swarm of earthquakes lasting a few hours'.

This will indicate magma is moving upwards and getting primed to blow.

The Icelandic Met Office (IMO) has already increased the Aviation Colour Code for the volcano from green to yellow as a precaution.

The icy roof of Grímsvötn means its eruptions are not as catastrophic as those of other volcanoes.

The ash spewed out by the blast collides with a wall of ice, which can be up to 850 feet (260 metres) thick, and clumps up.

Instead of being a fine debris that lingers in the atmosphere, it becomes wet and sticky and plummets from the air quickly, limiting disruption and damage.

'Ash clouds therefore only travel a few tens of kilometres from the eruption site,' says Dr McGarvie.

'This is a good scenario for Icelanders and also for air travel, as it prevents the formation of substantial ash clouds that could drift around and close off airspace.'