Iceland's Eyjafjoell volcano has emitted massive amounts of ash since it began erupting a month ago and there is no end in sight, experts have said. "Since the beginning of the eruption, we estimate that 250 million cubic metres of tephra (ash and other fragmental material) has been produced," Icelandic geophysicist Magnus Tumi Gudmundsson said. The eruption, which began on 14 April, had peaked three times, he said: "in the first four days of the eruption, then on 5 and 6 May, and again last Friday." 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.