Geoscientists at the British Geological Survey (BGS) group asked members of the public for help on Wednesday with observations of volcanic ash from the eruption of the Grimsvotn volcano in Iceland.

BGS scientist Aoife O'Mongain said the group has developed a simple online questionnaire with questions like: 'Have you seen ash/dust on your car windshield?' and 'Have you smelt sulfur (rotten eggs)?' which should help map the ash's reach.

There is a short time window for ash observations for this eruption so any observations are welcomed, especially within the next 24 hours, O'Mongain said in a statement.

A map showing real-time survey results can be viewed by following the link at www.bgs.ac.uk.

The ash cloud from Grimsvotn belched as high as 20 km (12 miles) into the sky after the eruption on Saturday, but it did not trigger the kind of travel chaos caused by Iceland's Eyjafjallajokull eruption last year, which caused a six-day European airspace shutdown and cost airlines $1.7 billion.

The BGS said responses to the survey would help its scientists confirm the results of ash dispersion models on which flight cancellations are based.

Samples of ash are also being collected from across the country and will be analyzed for more insight into the types of ash that are reaching Britain, it said.

David Rothery of Britain's Open University Volcano Dynamics Group said he was cautiously optimistic that the main ash-producing phase of this eruption had now come to an end.

(Reporting by Kate Kelland, editing by Paul Casciato)

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