The city's 16 large and medium-sized reservoirs presently hold 1.31 billion cubic meters of water. Beijing's water supply bureau said consumption totaled 3.45 billion cubic meters last year, including 1.49 billion cubic meters of drinking water.

The city is home to 15.36 million permanent residents and over four million transients.

Most of Beijing's surface water resources are stored in reservoirs but even the Miyun Reservoir -- the largest storage facility in North China -- holds only 992 million cubic meters of water this year.

The reservoir, with a capacity of 4.375 billion cubic meters, provides two thirds of the drinking water for the Beijingers and needs at least one billion cubic meters to maintain supplies, said Jiao Zhizhong, director of Beijing water supply bureau.

Drought prevention officials say Beijing will maximize storage at reservoirs, rivers and lakes and will take every opportunity to create artificial rainfall in reservoir areas.

Meanwhile, meteorologists have predicted the drought will ease, but have warned of torrential rain and mud-rock flows to come over the next three months.

Beijing's flood control and drought prevention headquarters has dispatched teams to monitor reservoirs, lakes, riverbanks and residential areas in downtown Beijing.

Before the end of June, the city will set up rainfall surveillance stations at major Olympic facilities under construction to monitor the volume of rain.

Beijing has suffered drought for seven consecutive years. The Beijing News reported the average annual rainfall between 1999 and 2005 was only 70 percent of the annual average since records began.

Throughout 1999, the city had only 349 millimeters of rainfall, about 58.7 percent of the annual average, it said.

"The message is you get ready every year, because there is no certainty your home will not receive the full force a major landfalling hurricane," he said at a conference on hurricane preparations.

Fugate said that taking into account today's demographics, a hurricane similar to the one that killed 372 people in Miami in 1926 would be far more devastating if it hit today, and would cause about 100 billion dollars in damage.

Florida officials are particularly worried about the possibility a hurricane could smash an aging levee that rings the 1,800-square-kilometer (700-square-mile) Lake Okeechobee, in central Florida, which provides drinking water to millions of people.

A recent official report shows there is a 50 percent chance the dike could break within the next four years.

"If there is a breach in Lake Okeechobee it would be ugly," said Florida Governor Jeb Bush, who hosted the conference in Fort Lauderdale, Florida.

He said he discussed the issue with his brother, US
President George W. Bush, and stressed federal aid would be needed to reinforce the levee and to prepare for a possible evacuation of the 40,000 people who live around the lake if a major hurricane threatens the area.

"I think it's appropriate not to have people panic, but this needs to be a high priority in Washington, and I intend to lobby to make sure that it is," the governor said.

Should a major hurricane pound the area, Florida officials could face the formidable challenge of evacuating residents from both the Atlantic and the Gulf coasts of Florida, as well as those who live around the lake.

But officials insisted that people not in an immediate danger zone should batten down at home rather than join an exodus that could easily clog highways.

"The nightmare scenario would be having people stuck in gridlock when a major hurricane makes landfall ... people would drown, cars would flip over as trees come falling down," said Max Mayfield, who heads the Miami-based
National Hurricane Center.

Making matters worse, some 100,000 people displaced by the hurricanes that slammed parts of the US Gulf coast and southeast Florida last year are still living in temporary shelters, mostly trailers and mobile homes that offer little protection from the killer storms.

In addition, thousands of home owners have yet to fix roof damage caused by last year's hurricanes.

Researchers at the University of Colorado say they expect nine hurricanes, five of them particularly intense, to form in the Atlantic basin during the season, which officially runs from June 1 to the end of November.

After a helicopter inspection of the active volcano, Vice President Jusuf Kalla called central Java's government authorities to evacuate residents living in danger zones to makeshift shelters.

"We shouldn't wait until the alert status is raised into the highest level, because volcanologists had says (Merapi) may erupt any day," Kalla said after he held a meeting with local government officials at nearby district town of Magelang.

Kalla urged that all residents living at a radius of 12km from Merapi's crater to leave immediately.

While volcanologists said the red-hot lava sliding down Merapi's west side towards Krasak river is a new development, they added that the 1 500-metre long flow is still far away from any inhabited areas.

Triyani, an expert at Yogyakarta's Agency for the Assessment and Application of Technology, told Deutsche Presse-Agentur dpa that molten lava was also flowing 200m down the south side of Merapi.

"Looking into this new phenomenon, we feared that the molten lava may flow from Merapi's crater to all direction should the volcano erupt," Triyani said.

Merapi, about 450km south-east of Jakarta, began heating up a month ago and volcanologists upgraded the alert status to level three on April 12.

Though volcanologists have not raised the alert status to the highest level of four, which would require a mandatory evacuation for those living on the slopes, Kalla said, "It's time now to evacuate residents in the danger zones."

Volcano watchers have warned that a new dome of lava on Merapi's peak, which has been growing rapidly in the last two weeks, could cause superheated streams of gas to travel down the mountain sides should it collapse.

"It's very unlikely that Merapi will have a vertical eruption," said another volcanologist Subandriyo. "But the danger is with heat clouds and ash."

During the last eruption in 1994 hot gas clouds, locally called "shaggy goats," travelled at fast speed several kilometres down from the summit and killed at least 66 people, mostly from horrific burns.

Only over 5 000 of about 30 000 residents have already been evacuated to temporary shelters, but many thousands of others have been reluctant to leave the mountain, preferring to take the advice of local mystics who believe Merapi will only erupt after certain omens come, including mysterious beams of light shining over its steep flanks.

The mountain has spiritual significance for many Javanese and is one of only four places where the royal palaces of Yogyakarta and Solo make offerings to placate the ancient Javanese spirits.

The 2 968-metre-high Merapi is one of 65 volcanoes listed as dangerous in Indonesia. The volcano's most deadly eruption took place in 1930, when 1,370 people were killed.

Indonesia has the world's highest density of volcanoes, with 500 located in a so-called "Ring of Fire," along the 5 000km wide archipelago nation. Of these, 128 are active. - Sapa-dpa

A couple in their 80s were found dead in a destroyed mobile home in Westminster, about 45 miles northeast of Dallas, Collin County Fire Marshal Steve Deffibaugh said. A 14-year-old boy was killed in neighboring Grayson County when a chimney collapsed on the stairwell where he had taken shelter, authorities said.

"It sounded like a regular thunderstorm, then it went crazy," said Cathy Dotson, who huddled on the floor of her Westminster home with her grandchildren when the tornado hit Tuesday night. "I could actually feel my house move."

Christy Adame, who lives a half-mile from the home where the elderly couple died, took shelter in a closet with her husband and two sons.

When they emerged, she found her horse barn gone, one of her horses dead in a tree and the smell of propane so strong - and the risk of an explosion so high - that officials would not let a neighbor shoot his suffering cow, which had been impaled on a two-by-four.

"Now I know what an earthquake feels like," Adame said.

Collin County spokeswoman Leigh Hornsby said crews went door-to-door checking homes early Wednesday to make sure there were no more victims, and believe everyone was accounted for. The dead were identified as Paul Harris Newsom, 82; his wife, Mary Ellen, 80; and Colson Owens, 14.

Deffibaugh said the twisters took Westminster's residents "by surprise, totally unaware." The community of about 420 has no sirens, and the tornadoes hit too fast for the county's emergency telephone-notification system to respond, he said.

National Weather Service meteorologist Alan Moller said at least two tornadoes hit. "I think it was the first tornado that killed three people," he said. "Then there was a larger tornado after that that probably did extensive damage."

The damage track was estimated at a half-mile wide and 6 to 7 miles long.

Storms also raked Arkansas early Wednesday, toppling trees, damaging roofs and downing power lines. Students at a Little Rock junior high school were evacuated to a high school next door after a tree fell near fuel tanks. A FedEx truck was blown into the median of Interstate 530.

In western Kentucky, flooding caused by heavy rains forced at least nine homes to evacuate and several people had to be rescued from the tops of their cars, said Melissa Rowland, emergency management director in Carlisle County.

McCann helped lead the study, which the California Department of Water Resources launched after Hurricane Katrina. The goal was to help the state calculate the effect of a major earthquake or winter flooding in the Delta region.

In the hypothetical disaster scenario presented Wednesday, seismic waves would trigger the collapse of the earthen levees, causing waves of salt water from San Pablo Bay to rush into the Delta.

An earthquake this size has a relatively low probability of occurrence -- a 6.8 percent chance in 50 years. "That seems remote, but not given the size of events that would transpire,'' Galloway said at a news conference.

"A realistic look at the Sacramento Delta will make us wise and more aware,'' McCann said. "Once we understand the risk, we can decide how to design, build and operate a levee system. The public can decide what the investment should be.''

The study uses a mathematical modeling system of the San Francisco Bay and Sacramento-San Joaquin Delta to identify which regions would be breached and flooded. The model takes into account the Delta region's normal flows, barrier operations, control gates and other structures.

There are 1,100 to 1,600 miles of levees in the Delta and Suisun marshes.

While winter flooding is an ongoing concern, an earthquake would be far more catastrophic, according to scientists at the Stanford conference.

The foundations of the state's levees, old and poorly maintained, are built on sandy and silty soil, scientists said. In an earthquake, the soil could liquefy and collapse.

And large waves could form in the flooded Delta, eroding more levees, the study predicts.

The most immediate danger would be to the 400,000 people who live in the Delta region, McCann said.

"There is no warning for the people who live in the region, no opportunity for evaluation. There are just moments to get out," he said.

It would also affect businesses and an estimated 85,000 acres of farmlands. About $400 billion of the state's annual economy is dependent, either directly or indirectly, on the Delta, McCann said.

Galloway urged the state to invest in levee improvements. "You can't not do it and think you're protected," he said.

Said McCann: "It is a wake-up call for California and the nation about the level of protection provided by levees, and the exposure we have in the event of a failure."

The 5.1-magnitude quake was centered 11.6 miles south of Hualien, the weather bureau said.

Hualien lies on Taiwan's east coast, about 60 miles southeast of the capital, Taipei.

Quakes frequently rattle Taiwan, but most are minor and cause little or no damage. However, a 7.6-magnitude earthquake in central Taiwan in September 1999 killed more than 2,300 people.

Oddball meteorite

Scientists have collected thousands of various meteorites over the years and tell them all apart by their various structural, chemical, and mineralogical compositions. The specific concentrations of platinum group elements in the newfound 10-inch (25 centimeter) meteorite place it in the "LL-ordinary chondrite" group of meteorites.

But other characteristics set it apart from the group, such as having silicate and sulfide minerals rich in iron, but no metallic iron-nickel phase.

"So it is 'another kind' of LL-ordinary chondrite that we do not have in our collections," said study co-author Alexander Shukolyukov of the Scripps Institution of Oceanography and the University of California, San Diego.

A potential implication of this odd meteorite, he said, is that the bombardment of meteorites 145 million years ago was different than those crashing into Earth more recently.

The researchers can't say for sure why this fragment is preserved. Current models indicate that no unaltered fragments can survive large impacts, which, Shukolyukov suggests, implies the models are incomplete.

Just a remnant

It is also clear that it was much, much larger than 10 inches in diameter when it smacked the surface.

An 820-foot-diameter (250 meters) meteorite would slam into the planet and release energy on the order of about 1,000 megatons-about 66,000 times the strength of the 15-kiloton bomb dropped on Hiroshima. The impact would create a crater 3 miles (5 kilometers) across, Shukolyukov told SPACE.com.

In contrast, the Morokweng crater is a whopping 43 miles across (70 kilometers), so the meteorite that created it must have been substantially bigger than 820 feet.

The raw energy produced by the impact also generates a lot of heat - 3,100 to 24,700 degrees Fahrenheit (1700 to 13,700 Celsius) - so it's surprising that anything remains of the rock at all, and even more so that it is unaltered. Generally the heat completely melts or vaporizes meteorites, and if anything is left, it doesn't resemble its original state.

"It may be that this fragment was just a separate small meteorite that accompanied a 'big guy," Shukolyukov said.

However, according to the models, a trailing object would have completely melted.