LONDON — Volcanic ash blanketed parts of rural Iceland today and left a widening arc of grounded aircraft across Europe, as thousands of planes stayed on the tarmac to avoid the hazardous cloud. Travel chaos engulfed major European cities and the U.N. warned of possible health risks from falling ash.

Anxious Polish officials fretted that the ash cloud could threaten the arrival of world leaders for Sunday’s state funeral of President Lech Kaczynski and his wife, Maria, in the southern city of Krakow. So far, President Barack Obama, Russian President Dmitry Medvedev and German Chancellor Angela Merkel are among those coming and no one has canceled. Kacyznski’s family insisted they wanted the funeral to go forward on Sunday.

Eurocontrol, the European air traffic agency, said the disruptions that upended travel in Europe and reverberated throughout the world Thursday were even worse today, with only 11,000 flights expected to operate instead of the usual 28,000. It said delays will continue into Saturday as the ash cloud moves south and east.

Travelers jammed train stations and hotels in key European cities. Rose Teunissen, a spokeswoman for Dutch train company NS Hispeed, said extra trains were put on and lines to buy train tickets at Amsterdam’s Schiphol Airport were so long the company was handing out free coffee.

Thalys, a high-speed joint venture of the French, Belgian and German rail companies, was allowing passengers to buy tickets even if the trains were fully booked.

“We think we can help a lot of passengers get closer to their final destinations,” said Thalys spokeswoman Patricia Baars.
Aviation experts said it was among the worst disruptions Europe has ever seen.

“We don’t have many volcanoes in Europe,” said David Learmount of Flight International, an editor at the aviation publication. “This one is right out there on the extreme edge of what you would consider Europe – but the wind was blowing in the wrong direction.”

Ice chunks the size of houses tumbled down from a volcano beneath Iceland’s Eyjafjallajokull (ay-yah-FYAH’-plah-yer-kuh-duhl) glacier Thursday, as hot gases melted the ice. The volcano began erupting Wednesday for the second time in less than a month.

As torrents of water roared down the steep slopes of the volcano, about 40 people nearby were evacuated because of flash floods, which washed away chunks of the country’s main ring road. More floods from melting waters are expected as long as the volcano keeps erupting, said Rognvaldur Olafsson of the Civil Protection Department.

The ash cloud, drifting between 20,000 to 30,000 feet (6,000 to 9,000 meters) high and invisible from the ground, left tens of thousands of travelers stranded around the globe and blocked the main air flight path between the U.S. east coast and Europe.

Fearing that microscopic particles of highly abrasive ash could endanger passengers by causing aircraft engines to fail, authorities shut down air space over Britain, Ireland, France, Denmark, Norway, Sweden, Finland and Belgium. That halted flights at Europe’s two busiest airports – Heathrow in London and Charles de Gaulle airport in Paris – as well as dozens of other airports, 25 in France alone.
As the cloud moved east, flights were halted Friday at Frankfurt airport, Europe’s third-busiest terminal, and at 10 other German airports including Duesseldorf, Berlin, Hamburg and Cologne. No flights were allowed either at the Ramstein Air Base, a key U.S. military hub in southwestern Germany.

Only about 120 trans-Atlantic flights reached European airports this morning, compared to 300 on a normal day, said Eurocontrol’s Evans. About 60 flights between Asia and Europe were canceled.

The U.S. Geological Survey said about 100 aircraft have run into volcanic ash from 1983 to 2000, sometimes losing power in their engines, but there have been no fatal incidents. Still, authorities are very wary, because ash cannot be detected by a plane’s normal weather radar.

Air space restrictions were lifted or imposed or extended as the cloud moved east and south. Aviation authorities in Ireland reopened airports in Dublin and Cork and France allowed some planes to land at Paris’ three airports during a four-hour window today.

Sweden and Norway declared skies in the far north to be safe again for travel even as flights in both capitals – Stockholm and Oslo – were still on a lockdown. Norwegian Prime Minister Jens Stoltenberg, who was in New York, managed to get a flight to Madrid, but aides said they were still not sure when or how he would get back to Norway.

Slovakia closed its airspace and Poland expanded its no-fly zone today to most of the country, excluding the southern cities of Krakow and Rzeszow. Belgium extended its flight restrictions until late Saturday morning.

NATS, the private company that controls British air space, said the air over England would remain closed at least until 1 a.m. Saturday (0000 GMT, 8 p.m. EDT Friday) but some international flights were allowed into and out of Northern Ireland and western Scotland.
Britain’s Meteorological Office said the wind was expected to blow form the north, which would bring further ash across parts of Britain. Small amounts of ash settled in Iceland, northern Scotland and Norway.

Professor Jon Davidson of the Department of Earth Sciences at Durham University in England said the dispersal of the cloud is dependent on the weather. The cloud can be blown elsewhere, the ash could all fall to Earth, or the ash particles spread and become diluted, no longer posing a threat to aircraft, he said.

The World Health Organization in Geneva said the ash cloud mostly remained high in the atmosphere on Friday, but it could pose a health risk if particles reached the ground. It advised Europeans to try to stay indoors if the ash fell, because inhaling the particles can cause respiratory problems, especially for those suffering from asthma and respiratory diseases.

The volcano caused ministers and officials from at least 12 countries to miss the start of a European Union finance ministers meeting in Madrid.

Iceland, a nation of 320,000 people, sits on a large volcanic hot spot in the Atlantic’s mid-oceanic ridge, and has a history of devastating eruptions. One of the worst was the 1783 eruption of the Laki volcano, which spewed a toxic cloud over Europe with devastating consequences.