The fire, which began when falling tree dragged a power line to the ground, left patches of dense trees and brush "totally nuked, completely black," said Steve Segin, a spokesman for the Rocky Mountain Incident Management Team.

No structures were reported lost but a house suffered exterior damage. A six-mile stretch of Colorado 96 was closed.

Judi Coker, who lives about two miles from the fire, said less smoke was visible Thursday than a day earlier. Her subdivision was not threatened and she and her husband, Rod, were not among the residents who left, but their bags were packed just in case.

"It's very dry, more dry than I've seen it since we lived here," said Coker, who has lived in the area for four years.

The Rocky Mountain Area Predictive Services issued a red-flag warning for a huge swath of southern Colorado, meaning conditions were favorable for big, fast-moving fires. The warning spanned the entire width of the state and ranged as far north as the Denver area.

At least 60,604 acres have burned in Colorado this year, said Larry Helmerick, spokesman for the Rocky Mountain Area Coordination Center. That compares with 41,048 acres for all of 2005. It was still far below the 619,029 that burned in 2002.

"It's so dry out here that it doesn't take more than a spark to start a wildfire," said Jamie Moore, director of emergency management for Douglas County south of Denver, where a passing train apparently sparked a 30-acre fire Wednesday.

In northwestern Colorado, a 3,700-acre fire quieted down after high winds blew in a mild cold front, said fire information officer Pam Wilson. One abandoned cabin burned.

More than half of Colorado is experiencing severe or extreme drought, according to the National Drought Mitigation Center. Arizona is almost entirely under extreme drought conditions.

In Arizona, fire crews quickly responded to a 120-acre blaze that broke out Wednesday afternoon on the west side of Flagstaff, a city of 60,000 people nestled in a thick pine forest. The blaze was contained Thursday morning, but the threat was enough to evacuate 1,000 homes.

Officials credited the quick response of air tankers and extensive forest thinning.

Jim Wheeler, the assistant fire chief in Flagstaff, passed the word to a meeting of evacuees Thursday that all the area's homes were saved.

"Your neighborhoods are in fantastic shape," he said to loud applause.

In Alaska, a wildfire only a few miles northeast of the small town of Anderson grew to 65,500 acres. The town, 75 miles southwest of Fairbanks, was not in immediate danger, fire officials said Thursday.

Nearly 300 firefighters fought a 2,500-acre fire on the Utah side of Navajo Mountain on the Navajo Indian Reservation. The blaze was believed to have been started by lightning Saturday, said Jim Whittington, a U.S. Bureau of Land Management fire information officer in Kingman, Ariz.

So far this year, nearly 2.9 million acres have burned. That is more than three times the average by this time of year, according to the National Interagency Fire Center, but much of the acreage came in huge grass fires that swept Oklahoma and Texas this spring.

Without the once-dependable daily showers, lawns have browned, rice and sugar cane crops are suffering and residents have emptied store shelves of hoses and other irrigation devices.

The increase in watering could stress city and parish pumping systems, and officials fear they could break because of ground subsidence caused by the lack of rain.

"A tropical storm would do wonders for us right now," Keim said. "A weak one, of course."

The forecast for rest of the month calls for little or no rain, said Mike Shields, senior forecaster at the National Weather Service office in Slidell. Shields said there will be a chance for only spotty showers over the weekend.

"And then until the end of the month, it looks like the same pattern of high pressure still over us and keeping us dry," he said.

Southern Louisiana had been abnormally dry for about five months before the storm made landfall Aug. 29., Keim said.

"The drought was interrupted, if you will, by Katrina, and we went back into the drought pattern. Then we got that deluge from Rita. And as soon as that storm left, we went right back into the drought pattern," he said.

Normally, humidity rises into the sky, forming a cloud and then rain. But Keim said a stable structure of atmosphere is hanging over the region, preventing the moisture from rising, similar to the atmospheric conditions in normally arid states.

"For whatever reason, this dome of upper pressure in the atmosphere seems displaced east by a few hundred miles," Keim said.

The National Weather Service predicts that rain in the area will return to normal levels over the next three months. But Keim said such predictions typically can be way off.

"We're crossing our fingers," forecaster Tim Destri said. "We can't say for sure, but we see some hope of getting back to the typical summer pattern."

The quake was considered minor, said Dale Grant, a geophysicist with the National Earthquake Information Center.

"A quake of this magnitude generally won't cause a great deal of damage, if any," he said.

Still, emergency dispatchers took a flood of worried calls from people asking if they had heard an explosion or plane crash.

"Oh Lord, after it happened every line in here lit up," Jackson County dispatcher Belinda Clawson said.

Arthur Buchanan said he didn't hear anything while working inside P.J.'s Fast Food Mart in Sylva, but he felt the store tremble.

"I figured somebody had ran into the side of my building," he said, "because it shook it good."

Over the past year, four of six other noticeable quakes within 60 miles of Thursday's epicenter were bigger, according to the center. They include a 3.7-magnitude temblor in August centered in Madison County that shook houses as far south as Athens, Ga.

He said rescuers concluded that both men were killed by the heat of the cloud, estimated at around 400 degrees Celsius (750 degrees Fahrenheit).

The pair were helping people evacuate their village when the heat cloud and molten lava struck. They were the first human casualties since Merapi began showing increased activity in April.

The condition of the bodies was similar to having been "baked in an oven," a rescue worker who went inside the bunker using heat-protected clothing told an AFP journalist at the site.

Merapi has been emitting deadly heat clouds that can reach temperatures up to 500 degrees Celsius.

Wednesday's large emission led scientists to place Merapi back on its highest alert, meaning they believe an eruption is imminent, a day after they had downgraded it.

On Friday the volcano emitted three heat clouds five kilometers down its southestern slopes, near the site of the bunker where the men were killed, said Triyani of the volcanology office in nearby Yogyakarta city.

She said the men had had ample time to flee.

"They should have fled when there was a sign that the cloud was coming. We don't know the condition of the bunker, whether it's up to standards," she told AFP.

One man who witnessed Wednesday's eruption and was a friend of one of the victims said the two could have survived if they had fled immediately.

"His motorcycle was on stand-by. He shouldn't have entered the bunker," the man told ElShinta radio.

Sunartono, a local relief official, said the bunker had been designed to protect people from passing heat clouds and that the men had died because the bunker was buried under 2.5 meters (yards) of thick hot molten rock.

"Because the bunker was covered by extremely hot materials, the temperature inside was also very hot," he was quoted as saying by the Detikcom news webiste.

About 15,000 villagers sheltering in makeshift camps in safe areas had just begun returning home Wednesday when the heat clouds appeared. The volcano had been on red alert since May 13.

Merapi has shown fluctuating volcanic activity since mid-May but appeared to stabilise after a lava dome that had been forming at its peak partially collapsed last Friday.

Merapi's deadliest eruption was in 1930 when more than 1,300 people were killed.

Five people were killed during the week in neighbouring Tripura state where 10,000 residents were also displaced.

In Assam, where 13 of the 27 districts are flooded, an estimated 485,000 people were displaced and large areas submerged, a government statement said. Many have taken refuge in temporary camps.

Police and rescue workers with boats were deployed in the worst-hit Cachar and Karimganj districts in southern Assam to evacuate villagers.

"The situation is critical and with road links snapped we may have to requisition helicopters to drop essentials to people staying in makeshift camps located in inaccessible areas," Cachar district magistrate Gautam Ganguly said by telephone.

Road and rail communications were disrupted in many parts of Assam with floodwaters covering highways and rail tracks.

The Indian army Thursday rescued scores of passengers from southern Assam after a train in which they were travelling was stranded.

According to a Central Water Commission bulletin, the main Brahmaputra river was flowing above the danger level in at least seven places in Assam.

Floodwaters had entered Kaziranga National Park, home to the endangered one-horned rhinoceros, and forced animals to migrate to higher ground.

The 2,906-kilometer (1,816-mile) river -- one of the longest in Asia -- traverses Tibet, India and Bangladesh before emptying into the Bay of Bengal.

Every year the monsoon causes the river to flood in Assam, a remote state of 26 million people. In 2004, at least 200 people died and millions were displaced.

A spring that feeds the Oujiang lies close to the blast site. Large amounts of sand and stones were trucked to the site in an effort to prevent any waste water from contaminating the river, Xinhua said.

One person was injured and two people were reported missing after the blast, it said.

In the Dasha river spill, a truck overloaded with 60 tons of coal tar - a substance linked to cancer - crashed Monday and dumped its contents into the river. Measurements Friday showed that levels of phenol, also known as carbolic acid, were 100 times greater than acceptable levels in some spots.

Cleanup crews scrambled Friday to absorb the toxic substance before it reaches the Wangkuai Reservoir of Baoding, a city of about 10 million people, Xinhua said.

It said a dozen fire engines were pumping polluted water downstream from the spill site and trucking it to a "closed environment" where it could be treated, without giving specifics.

The pollution was said to be traveling about nearly 1 mile per hour downstream toward Baoding, which is about 45 miles from the site of the accident.

The day after the spill, the pollution had reached Hebei's Fuping county, where some 50,000 residents rely on the river for drinking water. Fuping residents were told to take water from nearby reservoirs and seven standby wells until the river could be cleaned, Xinhua said.

Liu Qing, a villager who lives along the Dasha in Fuping, said by telephone that the water was not discolored and did not have any unusual odor but that she had this week noticed dozens of dead fish floating in the river.

Liu said her family normally drinks well water, not water from the river, so they have not been affected.

Another Fuping resident, Li Xingcui, said her family was still using the water to wash vegetables and take baths, ignoring warnings aired on local television. She said the water looked and smelled normal.

Li's family was taking water from a mountain stream for drinking.

Prolonged exposure to coal tar has been linked to increased rates of certain types of cancer but it is also used in small doses as a topical medicine to treat eczema and other skin diseases, according to the World Health Organization's International Agency for Research on Cancer.

Many of China's canals, rivers and lakes are severely tainted by industrial, agricultural and household pollution.

In November, a major chemical spill on the Songhua River halted water supplies to tens of millions in China and Russia. Local authorities were accused of reacting too slowly and delaying public disclosure of the spill.

"The unique aspect of the Siberian loess permafrost is that it is quite deep - 20 to 40 meters - and has a surprisingly high carbon concentration at depth for a mineral soil," said Terry Chapin, co-author from the Institute of Arctic Biology at UAF.

"This paper explains the processes that led to the accumulation of large amounts of soil carbon and the processes that could lead to its return to the atmosphere."

The largest carbon reservoir on Earth is the ocean, which scientists estimate holds about 40,000 gigatons; soils contain about 2,500 Gt and vegetation about 650 Gt. According to the authors, about 500 Gt of carbon are contained in the thaw-threatened loess, also called yedoma, of Siberia and Alaska.

"I was surprised, because it is unusual to find major new large carbon stocks," Chapin said. "We have spent more than five years discussing among ourselves all the details of the calculations, because initially I did not believe that the pool could be both so large and so decomposible (once thawed)."

Permafrost has been seldom incorporated into global carbon budgets in part because the "... size of the carbon pool was so poorly quantified ... and in part because global data bases for soils have been standardized to provide data only for the top meter of soil," Chapin said.

"People know about carbon in permafrost - it's not a trivial amount," said Ted Schuur, co-author from the University of Florida. "Normally, scientists look for carbon in the upper layers of permafrost where organic matter decomposes."

Laboratory and field experiments by the scientists demonstrate that the organic matter in yedoma decomposes quickly when it is thawed and produces rates of carbon release similar to those of productive northern grassland soils.

"If these rates continue as field observations suggest, most carbon in recently thawed yedoma will be released within a century - a striking contrast to the preservation of carbon for tens of thousands of years when frozen in permafrost," state the authors.

The National Science Foundation provided financial support for this research.