Iceland's Eyjafjoell volcano, which continued causing flight chaos in Europe Monday, has emitted massive amounts of ash since it began erupting a month ago and there is no end in sight, experts said.
"Since the beginning of the eruption, we estimate that 250 million cubic metres (8.8 billion cubic feet) of tephra (ash and other fragmental material) has been produced," Icelandic geophysicist Magnus Tumi Gudmundsson told AFP.
The eruption, which began on April 14, had peaked three times, he said: "in the first four days of the eruption, then on May 5 and 6, and again last Friday."
On Sunday, Icelandic volcanologist Bjoern Oddsson, said volcanic activity had increased slightly since Friday.
"The column (of smoke) has increased and rises up to eight kilometres," he told AFP, as opposed to six kilometres in previous days.
Gudmundsson stressed that the ongoing Eyjafjoell blast "is a big eruption," adding that for Iceland it was "the biggest since the notorious eruption at (the neighbouring and much larger volcano) Katla in 1918."
"There is really no way of telling when it will stop. There has been quite a bit of earthquake activity underneath Eyjafjallajoekull (the glacier covering the volcano), which means that magma is still emerging," Gudmundsson said.
His comments came as authorities cautioned the volcanic ash cloud would ground 1,000 flights in Europe on Monday with airports in Britain and the Netherlands hit.
Domestic flights in Iceland were also disrupted Monday morning and international flights could be impacted later in the day, aviation officials said.
"The domestic airport in Reykjavik is closed, but those in Akureyri and Egilsstadir are still open," Hjoerdis Gudmundsdottir, a spokeswoman for Icelandic aviation authority Isavia, told AFP.
"The international airport in Keflavik is open at the moment but I expect it to close later today as the forecast says the ash will move further north, thus in the way of air traffic routes over Iceland," she said, adding that international flights so far were operating without disruptions.