Monitoring Glaciers To Watch Global Change

Since well before global warming became a heated political issue, scientists have been trying to determine the rate at which our planet’s temperature is increasing. While placing many thermometers around the world would appear to be the solution, local temperatures can vary widely across regions and from one year to the next. Instead, researchers have found they can obtain a measure of average global temperatures by using satellites to monitor heat-sensitive objects on the ground. Of these objects, glaciers are among the most reliable indicators of climate change.		Alpine glaciers, like this one near Mt. McKinley, Alaska, change in response to the local climate. By monitoring the change in size of glaciers around the world, scientists can learn about global climate change. (Photograph by Klaus J. Bayr, Keene State College, 1990)
		One method of measuring glaciers is to send researchers onto the ice with surveying equipment. The Muir Glacier, shown here around 1950, has been studied for over 200 years. (Photograph from the American Geographic Society Collection archived at the National Snow and Ice Data Center, University of Colorado at Boulder)
Despite typical glaciers’ massive sizes, monitoring them is not always an easy task. Only specific types of small glaciers are good measures of climate change. Some glaciers are too large to measure accurately, and others are simply too unpredictable. Once scientists find a suitable glacier, they must take satellite images of the ice for a minimum of five years and compare the results. They then have to look closely at the outside edge of the glacier (the glacier’s terminus). If a large percentage of the glacier’s edge is receding then the area around the ice is growing warmer, and if a large percentage is expanding then the area is growing cooler. When enough measurements from many different parts of the world have been gathered, the researchers can determine whether the earth is growing warmer or cooler.		The terminus of the Pasterze glacier, Austria. It dwarfs the three hikers at lower right. (Photograph by Klaus J. Bayr, Keene State College, 1988)

News Release : Scientists Find Part of New Zealand's Submerged "Pink Terraces"

They were called the Eighth Wonder of the World. Until the late 19^th century, New Zealand’s Pink and White Terraces along Lake Rotomahana on the North Island, attracted tourists from around the world, interested in seeing the beautiful natural formations created by a large geothermal system. But the eruption of Mt. Tarawera on June 10, 1886, buried the terraces in sediment and caused the lake basin to enlarge, engulfing the land where the terraces stood. For more than a century, people have speculated whether any part of the Pink and White Terraces survived the eruption.

This week, scientists from New Zealand’s GNS Science, one of several government laboratories, in collaboration with engineers and scientists from Woods Hole Oceanographic Institution (WHOI) and colleagues from Lamont-Doherty Earth Observatory of Columbia University and NOAA-PMEL, located portions of the long-lost Pink Terraces.

The research team, using autonomous underwater vehicles (AUVs) to map the bottom of Lake Rotomahana, are certain they have found the lower portions of the Pink Terraces on the lake floor. Project leader Cornel de Ronde, of GNS Science, said the team was elated by the discovery.

“The first sidescan sonar image gave a hint of a terraced structure so we scanned the area twice more and we are now 95 percent certain we are seeing the bottom two tiers of the Pink Terraces,” de Ronde said. 

Side-scan sonar and bathymetric data collected by two REMUS 100 AUVs clearly show crescent-shaped terraced structures in about 60 meters of water where the Pink Terraces were located prior to 1886. They are covered by a brownish lake sediment.

The free-swimming REMUS vehicles were developed by WHOI with funding from the US Navy and were operated by Amy Kukulya and Robin Littlefield of the WHOI Oceanographic Systems Laboratory (OSL) who travelled to New Zealand for the expedition.  Dan Fornari, a scientist with the WHOI Geology & Geophysics department, helped lead the expedition and, along with Marshall Swartz of the WHOI Physical Oceanography department, developed the underwater camera system used in the lake.

After detecting areas of interest with the AUV’s sonar systems, the team used the underwater camera system, developed with funds from the U.S. National Science Foundation, to capture images of the lake floor where they were able to photograph some of the stepped terrace edges.

Dr. de Ronde said the rest of the Pink Terraces were either destroyed during the eruption, or are still concealed under thick sediment not able to be penetrated by high-frequency AUV sonars.

The scientists found no sign of the larger White Terraces in the part of the lake that matched their location prior to 1886. The two terraces, part of a very large on-land geothermal system, were separated by several hundred meters prior to the eruption.  

There are very few examples of large land-based geothermal systems that have been torn apart by an eruption and become inundated in this way. Scientists hope the data collected during this expedition will help them better understand how geothermal systems respond to disruptions of this kind.

“It was very gratifying to take the tools and knowledge we’ve developed for ocean research and apply them to work in the lake, especially for a scientific project with so much Maori cultural significance.”

In 2009, WHOI signed a memorandum of understanding with GNS and New Zealand’s National Institute for Water and Atmospheric Research (NIWA) to expand research and technology development collaborations across the scientific disciplines in the southwest Pacific and within New Zealand territorial waters.  In addition to the work in Lake Rotomahana, the organizations are also collaborating on deep ocean research on the Kermadec Seamounts north of New Zealand’s North Island using the Sentry AUV and TowCam deep-sea imaging system.

“We hope the success in Lake Rotomahana is the first of many scientific collaborations in this part of the world where there are many interesting research problems to investigate.”

The project was a collaboration involving GNS Science, Woods Hole Oceanographic Institution in Massachusetts, Lamont-Doherty Earth Observatory at Columbia University in New York, the National Oceanic and Atmospheric Administration in Seattle, and the University of Waikato.

After this week’s discovery, de Ronde paid tribute to colleagues from WHOI, saying “This result would not have been possible without the team from Woods Hole Oceanographic Institution and their American colleagues. Their contribution has been huge.”

Why wars Happen?(1)

Many discussions of lies that launch wars quickly come around to the question “Well then why did they want the war?” There is usually more than one single motive involved, but the motives are not terribly hard to find.

Unlike many soldiers who have been lied to, most of the key war deciders, the masters of war who determine whether or not wars happen, do not in any sense have noble motives for what they do. Though noble motives can be found in the reasoning of some of those involved, even in some of those at the highest levels of decision making, it is very doubtful that such noble intentions alone would ever generate wars.

Economic and imperial motives have been offered by presidents and congress members for most of our major wars, but they have not been endlessly hyped and dramatized as have other alleged motivations. War with Japan was largely about the economic value of Asia, but fending off the evil Japanese emperor made a better poster. The Project for the New American Century, a think tank pushing for war on Iraq, made its motives clear a dozen years before it got its war — motives that included U.S. military dominance of the globe with more and larger bases in key regions of “American interest.” That goal was not repeated as often or as shrilly as “WMD,” “terrorism,” “evildoer,” or “spreading democracy.”

The most important motivations for wars are the least talked about, and the least important or completely fraudulent motivations are the most discussed. The important motivations, the things the war masters mostly discuss in private, include electoral calculations, control of natural resources, intimidation of other countries, domination of geographic regions, financial profits for friends and campaign funders, the opening up of consumer markets, and prospects for testing new weapons.

If politicians were honest, electoral calculations would deserve to be openly discussed and would constitute no ground for shame or secrecy. Elected officials ought to do what will get them reelected, within the structure of laws that have been democratically established. But our conception of democracy has become so twisted that reelection as a motivation for action is hidden away alongside profiteering. This is true for all areas of government work; the election process is so corrupt that the public is viewed as yet another corrupting influence. When it comes to war, this sense is heightened by politicians’ awareness that wars are marketed with lies.

Advanced economies at advantage in disaster recovery

A man sits surrounded by rubble after a magnitude 8.9 earthquake and tsunami in Rikuzentakata, northern Japan March 13, 2011.

The earthquake that devastated northeast Japan displaced the country's main island by 2.4 metres and even tilted the axis of the Earth by nearly 10 centimetres. The shock sounds awesome but it was imperceptible. History suggests the same will be true of the economic impact.

The instinctive reaction when viewing the extensive damage and frantic efforts to secure damaged nuclear reactors is to assume economic havoc will follow.

But researchers who have studied similar disasters in rich countries reach a reassuring conclusion: human resilience and resourcefulness, allied to an ability to draw down accumulated wealth, enable economies to rebound quickly from what seem at first to be unbearable inflictions - be it the Sept. 11, 2001, attacks on New York or Friday's 8.9-magnitude earthquake, the worst in Japan's history.

Japan itself provides Exhibit No. 1 in foretelling the arc of recovery. A 6.8-magnitude temblor struck the western city of Kobe on Jan. 17, 1995, killing 6,400 people and causing damage estimated at 10 trillion yen, or 2 percent of Japan's gross domestic product.

The importance of Kobe's container port, then the world's sixth-largest, and the city's location between Osaka and western Japan made it more significant for the economy than the more sparsely populated region where the latest quake and tsunami struck. Extensive disruption ensued, yet Japan's industrial production, after falling 2.6 percent in January 1995, rose 2.2 percent that February and another 1.0 percent in March. GDP for the whole of the first quarter of 1995 rose at an annualised rate of 3.4 percent.

"Despite the scale of the disaster, it is hard to find much evidence in the macroeconomic data of the effects of the Kobe earthquake," said Richard Jerram, chief Asian economist at Macquarie in Singapore and a veteran Japan-watcher.

Indeed, Takuji Okubo, chief Japan economist at Societe Generale in Tokyo, noted that Japan's economy grew by 1.9 percent in 1995 and 2.6 percent in 1996, above the country's trend growth rate at the time of 1.5 percent. Private consumption, government spending and, especially, public fixed investment all grew above average in 1995 and 1996, Okubo said in a report. By analogy, the medium-term impact on growth from the latest quake was also likely to be positive, he said.

Today's circumstances are, of course, different. Japan's economy has floundered in the intervening 16 years and its public finances have deteriorated. On paper, the country, is perhaps less well prepared at this stage of the economic cycle to pick itself up off its feet.

But Mark Skidmore, an economics professor at Michigan State University, attaches greater importance to a rich society's capacity to constantly adapt to the risks it faces. In the case of Japan, prone to regular earthquakes, this means improving its disaster response systems and adopting the latest techniques to help buildings withstand shocks.

Most of the damage wrought in Japan was by the ensuing tsunami, for which there was no time to prepare, and not by collapsing buildings - even though the quake was 1,000 times more powerful than the Kobe one.

"We don't know yet how devastating this is going to be economically, or even in terms of human casualties, but Kobe was able to rebound very quickly and I think there is the same potential here," Skidmore said in a telephone interview.

Skidmore and Hideki Toya from Nagoya City University in Japan have examined data for 151 countries over the period 1960-2003 and found that countries with higher levels of income, education and financial development suffer fewer losses from a natural disaster. Other researchers have reached similar conclusions.

"As incomes rise in a society, you can devote more resources to safety. So economies that have relatively high exposure to earthquakes or hurricanes start taking the precautions they need. Japan is among the best prepared in the world because they have high exposure and high income," Skidmore said.

Flooding at home not polar bears convinces people of man made climate change

Nick Pidgeon, Professor of Environmental Psychology at Cardiff University, showed for the first time that people with a direct experience of flooding are more likely to believe in man made climate change.

He said “scare” tactics, such as warning people of floods in Bangladesh or desertification in Sudan, are less likely to motivate people to take action.

“Polar bear images and melting glaciers do raise people's concern but they feel disempowered because they cannot do anything about it, whereas the local thing they understand,” he said.

The survey of 2,000 people in Britain, published in Nature, also found victims of floods are more willing to change their lifestyles to tackle global warming. For example by reducing energy use and taking less long haul flights.

Prof Pidgeon said people are becoming immune to the extreme risks of climate change in the Arctic and Amazon but they are likely to engage on the real risks of flooding and drought at home.

He also said people are more likely to act if they are given positive messages about what they can do.

“All the evidence shows you should be measured in showing people the risk but you can also be clear about the actions they can take. Scaring them will just put them off,” he added.

A separate study by the Carbon Trust found that more than half of people in Britain want big business to be more responsible when it comes to cutting greenhouse gas emissions.

However just seven per cent believe public announcements from a company about how it is reducing its impact on climate change are accurate

This week a number of initiatives to cut carbon are being held around the country for Climate Week, a nationwide event sponsored by Tesco and supported by Al Gore and Sir Paul McCartney.

The idea is to celebrate the positive things people can do to cut carbon emissions such as saving energy at home and taking public transport.

However campaigners say that some of the companies involved have failed to do enough to tackle climate change.

The World Development Movement claim that one of the main sponsors, the Royal Bank of Scotland, has invested more in coal-fired power stations than any other UK bank over the last few years.

As the Seasons Change, Will the Plankton?

Antonio Mannino had been at sea for more than a week, collecting samples of seawater and plankton and measuring the conditions in the North Atlantic Ocean. It was not exactly a luxury cruise, but to understand the planet’s biggest food source—phytoplankton—and perhaps its most important sink for carbon dioxide, you’ve got to get out on the water.

As is common in late autumn—when cold north winds of winter battle for supremacy of the North Atlantic against the lingering warm fronts of summer—the weather grew messy. Seas churned with waves rising seven to fourteen feet, and Mannino and colleagues struggled to cast water samplers and nets over the sides of the Delaware IIresearch vessel. After several days, the foul weather made it impossible to work, and the captain began steaming back from Georges Bank toward Provincetown, Massachusetts. He planned to lay anchor in the (hopefully) calmer waters of Cape Cod Bay and ride out the storm.

Mannino, an oceanographer from NASA’s Goddard Space Flight Center, was sitting in the ship’s galley, while graduate student Dave Munro dozed on a nearby couch. It was Friday the 13th.

Thud. Splash. Slosh.

A wave crashed through the porthole window, knocking out the glass and dousing Munro in a bath of seawater. A few tens of gallons sloshed around on the galley floor as the crew sealed the porthole hatch. No one was injured, and the ship was never in serious danger, but it was enough to send them back to port in Woods Hole.

The 155-foot Fisheries Survey Vessel Delaware II, operated by the National Oceanic and Atmospheric Administration (NOAA), is a 40-year-old workhorse. Spare parts are not exactly lying around on a shelf. So the crew did what seamen do: they bolted steel plates over the porthole, soldered things shut, and got back out to sea. There was research to be done, and time spent in port is time and money lost.

The 155-foot survey vessel Delaware II is operated by the U.S. National Marine Fisheries Service for studies of fish stocks and for support of basic research like CliVEC. (Photo courtesy Charles Byrne, NOAA.)

Mannino and colleagues from NASA, NOAA, and Old Dominion University headed back out into the North Atlantic for another week, sharing cramped quarters, cozy labs, and choppy autumn seas to see how those turbulent waters influence the tiniest and most important ocean life forms.

Laughter really is the best medicine (for leg ulcers)

Forget technology. The best prescription for patients with venous leg ulcers is good quality nursing care – and the occasional belly laugh!

A five-year study led from the University of Leeds has shown that ultrasound therapy does nothing to speed up the healing process of leg ulceration - contrary to what had been expected. Traditional methods of nursing care, which are cheaper and easier to deliver, work just as well, the authors conclude.

"The 'healing energy' of low-dose ultrasound can make a difference to some medical conditions but with venous leg ulcers, this is simply not the case," said Professor Andrea Nelson from the University of Leeds' School of Healthcare, who led the study.

"The key to care with this group of patients is to stimulate blood flow back up the legs to the heart. The best way to do that is with compression bandages and support stockings - not 'magic wands' - coupled with advice on diet and exercise. Believe it or not, having a really hearty chuckle can help too. This is because laughing gets the diaphragm moving and this plays a vital part in moving blood around the body."

Venous leg ulcers are common in people with varicose veins or mobility problems whose 'muscle pumps' in the feet and calves struggle to drive blood up to the heart. These ulcers can be painful and unsightly, having a significant negative impact on health and quality of life.

Although most leg ulcers will clear up with good nursing care, a significant proportion of the lesions will take 12 months or longer to heal. The older and larger ulcers become the harder they are to get rid of, hence the search for solutions that could speed-up the healing process.

A number of small studies had suggested that ultrasound could be the answer. Professor Nelson (University of Leeds), working with colleagues from the Universities of York and Teeside, and many NHS Trusts, have now shown that this is not the case.

The researchers concentrated on 'hard to heal' ulcers that had not cleared up after six months or longer. Drawing on patients from across the UK and Ireland, they found that adding ultrasound to the standard approach to care  - dressings and compression therapy - made no difference to the speed of healing or the chance of the ulcers coming back. Ultrasound also raised the cost of care per patient by almost £200.

"Rising levels of obesity mean that the number of people who suffer from legs ulcers is likely to grow," Professor Nelson said.  "We do need to find ways to helping those patients who ulcers won't go away, but our study shows that ultrasound is not the way to do that. We need to focus on what really matters, which is good quality nursing care. There really is no need for the NHS to provide district nurses with ultrasound machines. This would not be money well spent."

The study was funded by the National Institute for Health Research (NIHR) Health Technology Assessment Programme (HTA).

Full details of the findings are published online today in advance of publication in the British Medical Journal and Health Technology Assessment.

Siberia's Lake Baikal Feeling the Heat

The "Butterfly Effect" the idea that on a global scale, even small events can have a ripple effect around the world is demonstrated in the work of a Russian family in Siberia that have for three generations studied Lake Baikal -- one of the most biologically diverse of the world's oldest and deepest lakes. In the 1940's, Mikhail Kozhov began taking detailed measurements of the lake's temperature. His granddaughter, Lyubov Izmest'eva, continues the family tradition.

Izmest'eva ventures out onto the water, or ice in the winter, to collect water samples and measure temperatures, just like her mother and grandfather before her.

Along with a team of scientists from the University of California at Santa Barbara, Izmest'eva recently co-authored a study of Lake Baikal. The research sheds light on the way climate change is affecting temperatures in large bodies of water.

NEWS: Earth's Lakes Heating Up

"This consistent dedication to understanding one of the world's most majestic lakes helps us understand not only the dynamics of Lake Baikal over the past 60 years, but also to recognize future scenarios for Lake Baikal,” said lead author Steve Katz in a University of California at Santa Barbara press release.

"This work is important because we need to go beyond detecting past climate variation,” said Stephanie Hampton of the University of California at Santa Barbara in a press release by that school.

"We also need to know how those climate variations are actually translated into local ecosystem fluctuations and longer-term local changes. Seeing how physical drivers of local ecology –– like water temperature –– are in turn reflecting global climate systems will allow us to determine what important short-term ecological changes may take place, such as changes in lake productivity,” said Hampton.

“They also help us to forecast consequences of climate variability,” Hampton said.

NEWS: Lake Superior May Hit Record Temperature

The researchers found correlations between the lake and distant parts of the Earth. The results will help scientists understand how distant climate patterns affect the weather in central Asia.

For example, they found that changes in Lake Baikal's temperature varied along with monthly El Niño variations in the surface temperature of the Pacific Ocean, thousands of miles away.

The researchers also found connections between the jet stream and Lake Baikal. Three months after changes in the jet stream's strength and direction seasonal changes began to occur at the lake. Also, a less powerful jet stream resulted in less extreme cold spells in Lake Baikal.

Overall they found the lake is warming, but didn't find evidence of early springs or late winters.

The lake's temperature even reflected decade-scale changes in the Earth's rotation. Changes in the speed of Earth's rotation result in changes in the atmospheric zonal winds, the winds that travel east to west. The zonal winds affect the amount of energy available in the atmoshpere to cause storms in central Asia. And those long-term changes showed up in the Lake Baikal temperature record.

All of these forces influence each other and created a complex pattern of climate interactions. Lower El Niño forces correlated with a stronger Siberian high pressure center and a stronger jet stream flow. That resulted in more frequent cold snaps heading southeast across East Asia, including Lake Baikal, and more intense surface winds.

But even with the new understanding of climate interactions, some of the temperature changes in Lake Baikal remain unexplained.

Global warming may bring tsunami and quakes: scientists

- Quakes, volcanic eruptions, giant landslides and tsunamis may become more frequent as global warming changes the earth's crust, scientists said on Wednesday.

Climate-linked geological changes may also trigger "methane burps," the release of a potent greenhouse gas, currently stored in solid form under melting permafrost and the seabed, in quantities greater than all the carbon dioxide (CO2) in our air today.

"Climate change doesn't just affect the atmosphere and the oceans but the earth's crust as well. The whole earth is an interactive system," Professor Bill McGuire of University College London told Reuters, at the first major conference of scientists researching the changing climate's effects on geological hazards.

"In the political community people are almost completely unaware of any geological aspects to climate change."

The vulcanologists, seismologists, glaciologists, climatologists and landslide experts at the meeting have looked to the past to try to predict future changes, particularly to climate upheaval at the end of the last ice age, some 12,000 years ago.

"When the ice is lost, the earth's crust bounces back up again and that triggers earthquakes, which trigger submarine landslides, which cause tsunamis," said McGuire, who organized the three-day conference.

David Pyle of Oxford University said small changes in the mass of the earth's surface seems to affect volcanic activity in general, not just in places where ice receded after a cold spell. Weather patterns also seem to affect volcanic activity - not just the other way round, he told the conference.

LONDON'S ASIAN SUNSET

Behind him was a slide of a dazzlingly bright orange painting, "London sunset after Krakatau, 1883" - referring to a huge Asian volcanic eruption whose effects were seen and felt around the world.

Volcanoes can spew vast amounts of ash, sulphur, carbon dioxide and water into the upper atmosphere, reflecting sunlight and sometimes cooling the earth for a couple of years. But too many eruptions, too close together, may have the opposite effect and quicken global warming, said U.S. vulcanologist Peter Ward.

"Prior to man, the most abrupt climate change was initiated by volcanoes, but now man has taken over. Understanding why and how volcanoes did it will help man figure out what to do," he said.

Speakers were careful to point out that many findings still amounted only to hypotheses, but said evidence appeared to be mounting that the world could be in for shocks on a vast scale.

Tony Song of NASA's Jet Propulsion Laboratory in California warned of the vast power of recently discovered "glacial earthquakes" -- in which glacial ice mass crashes downwards like an enormous landslide.

In the West Antarctic, ice piled more than one mile above sea level is being undermined in places by water seeping in underneath.

"Our experiments show that glacial earthquakes can generate far more powerful tsunamis than undersea earthquakes with similar magnitude," said Song.

"Several high-latitude regions, such as Chile, New Zealand and Canadian Newfoundland are particularly at risk."

He said ice sheets appeared to be disintegrating much more rapidly than thought and said glacial earthquake tsunamis were "low-probability but high-risk."

McGuire said the possible geological hazards were alarming enough, but just one small part of a scary picture if man-made CO2 emissions were not stabilized within around the next five years.

"Added to all the rest of the mayhem and chaos, these things would just be the icing on the cake," he said. "Things would be so bad that the odd tsunami or eruption won't make much difference."

How Earthquake Happen?

World's largest earthquakes

How Tsunamis Occur

Japan: trying to fix nuclear plant cooling problem

A massive explosion has rocked a Japanese nuclear power plant after Friday's devastating earthquake.

A huge pall of smoke was seen coming from the plant at Fukushima and several workers were injured.

Japanese officials say the container housing the reactor was not damaged and that radiation levels have now fallen.

A huge relief operation is under way after the 8.9-magnitude earthquake and the tsunami it triggered, which is thought to have killed at least 1,000.

The offshore earthquake triggered a tsunami which wreaked havoc on Japan's north-east coast, sweeping far inland and devastating a number of towns and villages.

Japan's Prime Minister Naoto Kan declared a state of emergency at the Fukushima Daiichi and Daini (also known as Fukushima 1 and 2) power plants as engineers try to confirm whether a reactor at one of the stations has gone into meltdown.

The emergency declaration is an automatic procedure after nuclear reactors shut down in the event of an earthquake, allowing officials to take rapid action.

Evacuation zone expanded

Television pictures showed a massive blast at one of the buildings of the Fukushima-Daiichi plant, about 250km (160 miles) north-east of Tokyo.

A huge cloud of smoke billows out and large bits of debris are flung far from the building.

Japan's NHK TV showed before and after pictures of the plant. They appeared to show that the outer structure of one of four buildings at the plant had collapsed after the explosion.

The Tokyo Electric Power Co (Tepco), the plant's operator, said four workers had been injured.

It is not yet clear in exactly what part of the plant the explosion occurred or what caused it.

The Japanese government's chief spokesman, Yukio Edano, said the metal container around the reactor was not damaged in the explosion and that radiation levels in the area had actually decreased after the blast.Officials ordered the evacuation zone around the plant expanded from a 10km radius to 20km. BBC correspondent Nick Ravenscroft said police stopped him 60km from the Fukushima-Daiichi plant.

Japan's nuclear agency said earlier on Saturday that radioactive caesium and iodine had been detected near the number one reactor of the power station.

Japanese broadcaster NHK screened a before and after image showing the damaged Fukushima plant

The agency said this could indicate that containers of uranium fuel inside the reactor may have begun melting.

Air and steam, with some level of radioactivity, was earlier released from several of the reactors at both plants in an effort to relieve the huge amount of pressure building up inside.

Mr Kan said the amount of radiation released was "tiny".

Cooling system failure

Nuclear reactors at four power plants in the earthquake-struck zone automatically shut down on Friday.

In several of the reactors at the two Fukushima plants the cooling systems, which should keep operating on emergency power supplies, failed.

Without cooling, the temperature in the reactor core builds, with the risk that it could melt through its container into the building housing the system.

Pressure also builds in the containers housing the reactor.

Tepco said it was pumping water into the Fukushima-Daiichi's number one reactor in a bid to cool it down.

The reactors the plant are Boiling Water Reactors (BWR), one of the most commonly used designs, and widely used throughout Japan's array of nuclear power stations.

Continue reading the main story

• Japan quake: video reports
• How nuclear reactors work
• Quake: Wave forecast map

Analysts say a meltdown would not necessarily lead to a major disaster because light-water reactors would not explode even if they overheated.

But Walt Patterson, of the London research institute Chatham House, said "this is starting to look a lot like Chernobyl".

He said it was too early to tell if the explosion's aftermath would result in the same extreme level of radioactive contamination that occurred at Chernobyl.

The explosion was most likely caused by melting fuel coming into contact with water, he told the BBC.

The 8.9-magnitude tremor struck in the afternoon local time on Friday off the coast of Honshu island at a depth of about 24km, 400km (250 miles) north-east of Tokyo.

It was nearly 8,000 times stronger than last month's quake in New Zealand that devastated the city of Christchurch, scientists said.

Some of the same search and rescue teams from around the world that helped in that disaster are now on their way to Japan.

As relief workers begin to reach the earthquake zone, the scale of the damage is being revealed.

One of the worst-hit areas was the port city of Sendai, in Miyagi prefecture, where police said between 200 and 300 bodies were found in one ward alone.

The town of Rikuzentakada, in Iwate prefecture, was reported as largely destroyed and almost completely submerged. NHK reported that soldiers had found 300-400 bodies there.

Chief government spokesman Yukio Edano said it was believed that more than 1,000 people had died.

A local official in the town of Futuba, in Fukushima prefecture, said more than 90% of the houses in three coastal communities had been washed away by the tsunami.

Looking from the fourth floor of the town hall, I see no houses standing,'' Kyodo news agency quoted him as saying.