This false-colour image from an infrared satellite shows how the volcanic ash has spread over Europe. The ash shows up as red - however it can also be drawn up into clouds and is likely to be far more widely dispersed
This image from Nasa's Terra spacecraft shows how violently the volcano was erupting on April 15, when the UK closed its airspace. On the left is a natural-colour image while an infrared composite is on the right
A new satellite image of ash spewing from Iceland's volcano on 19 April from ESA's Envisat satellite. The visible plume is around 250miles long
The ash plume streams southwards over the Northern Atlantic Ocean in a satellite photograph from April 17. Thermal readings from the volcano vent reveal emissions equivalent to the energy consumed by 60,000 homes
The huge plume of ash thrown from the Icelandic volcano that has closed airports across Europe, may at last be dying down.
Scientists have revealed that although the volcano created powerful new tremors today, the eruptions are weakening and it is finally emitting less dangerous dust.
The cloud rising above the Eyjafjallajökull crater is now reaching a height of around 9,800ft according to the UK Met Office. Although a new eruption has pushed that back up to 13,000ft
Last week the tower of dangerous ash was 36,000ft high.
However, weather patterns continue to blow volcanic ash towards the UK.
Still British experts today said they were 'cautiously optimistic' that the ash could be on the wane.
Dr David Rothery, from the UK's Open University said: 'There is no high ash column rising above the vent.
'If this persists then the high altitude ash cloud will be starved of fresh air and eventually disperse.'
An official at Iceland's Met Office said ash production had fallen sharply and the nature of the eruption appeared to be changing.
'Our web cameras show that there is not much ash but mostly steam now,' said the geologist Hjorleifur Sveinbjornsson.
'The colour of the steam is brown but also quite white so it is more like water vaporising.'
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Scientists flying above the volcano said lava had burst from the crater and onto the Eyjafjallajokull glacier that sits atop the volcano.
The appearance of lava could suggest the eruption is moving into a less explosive phase.
Fewer explosions would mean less of the menacing ash that has drifted to the European continent, choking the upper atmosphere with tiny particles of glass and pulverised rock and causing countries across Europe to close their airspace.
There was still a risk, however, that molten rock could create new pathways for meltwater from the ice cap to run into the crater, causing more explosions and a higher level of ash production, he said.
The UK Met office is using both satellite images and a type of radar from the ground to keep track of the cloud. Infrared cameras are providing valuable data because ash particles interact with radiation in a different way to ordinary cloud particles.
This information is then used to create a real-time image of the skies over Europe.
A Met office spokesman said: 'Assuming the volcanic activity continues to weaken, we can expect ash clearance across the UK and we will be looking for the earliest opportunity that this might happen.'
However, those in Iceland may not be so lucky. Weather forecasts show a shift in winds to the north could cause ash to fall over the capital Reykjavick.
The Civil Protection Department have prepared plans for such an occurrence such as closing schools.
Iceland sits on a volcanic hotspot in the Mid-Atlantic Ridge and has relatively frequent eruptions, though most happen in sparsely populated areas and pose little danger to people or property.
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