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Archive for the ‘Physical Geography’ Category

Hurricanes might trigger big tropical earthquakes

Posted by Lindy on December 12, 2011

This is a very interesting idea but read it carefully to see what they are saying but also appreciate what they are not.

A new study by Professor Shimon Wdowinski may help scientists identify regions at high risk for earthquakes. By dumping rain and causing landslides, these storms can change the weight of the Earth in tectonically-stressed regions, releasing loads that had been keeping the faults locked in tight. The result is that faults already under pressure seem more likely to break in the years after very wet tropical cyclones.

Earthquakes including Haiti’s 2010 magnitude-7.0 temblor and a 6.4-magnitude quake that struck Kaohsiung, Taiwan, the same year, fit this pattern.  These quakes were preceded by drenching storms that wreaked other kinds of havoc. “The cyclone itself is a disaster, there is a lot of flooding, then there are landslides and then the earthquakes come,” Wdowinski said.

Disaster chain reaction

Widowinski became interested in whether tropical cyclones interact with earthquakes after noticing that both the 2010 Taiwan earthquake and the 2010 Haiti quake were preceded relatively closely by big storms. In the case of Taiwan, 2008’s Typhoon Morakot had dumped 115 inches (292 centimeters) of rain in just five days. In the case of the Haiti quake, the 2008 hurricane season had been brutal, with named storms (hurricanes and tropical storms) Fay, Gustav, Hanna and Ike tearing into the island. The researchers decided to see if the timing was a coincidence or whether it meant something more. They turned to Taiwan, which has good records of the past 50 years of quakes and storms.

Focusing only on very wet typhoons with the capacity to cause of a lot of erosion, and removing aftershocks that would bias the analysis, the researchers found that 85 percent of magnitude-6-and-above quakes occurred within the first four years after a very wet storm. That was five times what would have been expected from background quake rates. Even smaller quakes followed the same pattern, with 35 percent of magnitude-5-and-above quakes occurring within the first four years after wet storms — twice the expected number.

Timing is everything

Previous researchers have suggested that extremely low pressure from storms can trigger quakes in already-strained areas in the very short term but these longer-term linkages are likely caused by a different mechanism. These areas are already tectonically active, with faults building up strain as landmasses creep against one another. These strained faults are destined to rupture and eventually cause quakes.

But when a very wet typhoon or hurricane dumps lots of rain, it often causes large landslides in mountainous areas. Extra rain over the following months further erodes mountains and hills scarred by these landslides. This shifting of sediment lifts the weight that keeps faults locked. The burden lifted, the fault suddenly slips, causing a quake. These quakes are likely not any larger or smaller than they otherwise would have been, but the presence of very wet storms may give a hint that a quake-prone region is at higher risk of rupturing in the following years.

“The main engine that’s actually responsible for the earthquake is not the wet typhoon,” Wdowinski said. “The wet typhoon just determines the timing.”


Posted in Hazards, Physical Geography, Tectonics, Weather | Leave a Comment »

Queensland rebuilding ‘huge task’

Posted by alec8c on January 13, 2011 amazing pictures before and after shots of a back garden map of the flooding the very sad story of the boy who showed amazing bravery by telling rescuers to save his younger brother first

The Australian state of Queensland is facing a reconstruction task of “post-war proportions”, as floods left swathes of it under water.

State Premier Anna Bligh said the state was reeling from the worst natural disaster in its history. Powerful flood waters have surged through the state capital, Brisbane, leaving thousands of homes submerged. The floods peaked at a lower level than expected but more than 30 suburbs are under water. Huge amounts of debris – cars, boats and jetties – have been floating downstream, some smashing into bridges. One man died when he was sucked into a storm drain and two more deaths elsewhere were reported by Australian broadcaster ABC, bringing the toll from this week’s flooding to 15, with dozens more missing.

The Brisbane River is now receding and was expected to fall to around 3.2m by early on Friday. It peaked at 4.46m (14.6ft) just before 0530 (1930 GMT Wednesday), short of the 5.4m (17.7ft) in the 1974 floods. West of Brisbane, the small town of Goondiwindi is on high alert, with fears the flooding Macintyre River could swamp the town. Police are continuing to search areas of the Lockyer Valley for those missing after a torrent of water swept through the area on Monday.

“Queensland is reeling this morning from the worst natural disaster in our history and possibly in the history of our nation,” Ms Bligh told reporters.

“We’ve seen three-quarters of our state having experienced the devastation of raging flood waters and we now face a reconstruction task of post-war proportions.”

In Brisbane, the worst-hit suburbs included Brisbane City, St Lucia, West End, Rocklea and Graceville.

“There will be some people that will go into their homes that will find them to be never habitable again,” Ms Bligh said.

Brisbane Mayor Campbell Newman said 11,900 homes and 2,500 businesses had been completely flooded, with 14,700 houses and 2,500 businesses partially submerged.  

Milton resident Brenton Ward reached his home in the suburbs by rowing boat.

“We have water to the waist in the living room. We have to check the amount of damage – probably (the) electricity has to be all rebuilt,” he said.

Other residents said they felt lucky.

“I can handle this,” said Lisa Sully, who had some flood damage to her home in the suburb of Sherwood. “Mentally, I was prepared for worse.”

Many supermarkets in the city have been stripped of supplies, while a number of rubbish collections and bus services have halted. More than 100,000 properties had their power cut to reduce the risk of electrocution. Where waters had receded in the city centre, sticky mud remained. Officials said the clean-up could take months.

Brisbane airport survived the swell and remains open, with almost all flights unaffected. However, passengers are advised to check before travel. Public transport to the airport is severely limited. Extra police have been brought in to patrol the city.

The man who died was a 24-year-old who had gone to check on his father’s property and was sucked into a storm drain.

The bodies of two victims of floods earlier this week were also found, one in the Lockyer Valley and the other in Dalby, ABC said. Sixty-one people are still missing, with police very concerned about 12 people in the Lockyer Valley not seen since their homes were destroyed by a wall of water on Monday.

More rain caused by a cyclone off the Queensland coast is forecast for the next two days. The weeks of rain have been blamed on a La Nina weather pattern in the Pacific.

At the scene

Nick Bryant BBC News, Brisbane

Things are still very bad here – there is widespread devastation. Some 25,000 homes are either partially or totally flooded, but the key thing is the river levels didn’t peak at the high point feared.

The big commercial area will win a reprieve but more than 30 suburbs have been hit and people will be under water for days to come. There will have to be a huge recovery operation throughout the state, so this crisis is far from over.

The floods have devastated much of the agriculture sector and the mining sector. I was speaking to the state treasurer on Wednesday and he said the cost would have a “b” after it – for billions – rather than an “m”.

Eyewitness account:

Brisbane resident Rob Minshull tells the BBC’s World Today programme what life is like camped out on the roof of his home, waiting for the murky floodwaters to subside.

“My house is at least 15m (50ft) high so I’ve got the top deck of my home still free from the water but the rest of my house has gone under. I live opposite a park which is 5m under water – all I can see are the roofs of houses and the tops of trees.

There is one person left in the street along with me. I can see him on his roof; he’s about four houses down and we both have our mattresses on the roof.

We decided to stay, we told the emergency services we were staying, but everybody else has evacuated either by dinghy or several people climbed over the top of my roof. I’ve got the highest house in the street, and people were using my roof to get to houses on higher ground at the back.

That was several hours ago. Since then there have been lots of helicopters flying overhead. I’ve lost power and we’ve got no running water.

‘Ghost town’

The flooding has reached the bottom tier of my house, it’s about chest height. I’ve got brown waves going through the house – I’ve got snakes in the house. My cars are locked in the garage, I can’t get them out – they’re floating around, and banging in the garage.

We’re still expecting the waters to rise. Personally I’m fine; I’ve got a supply of fresh water, I’ve got my camping equipment and my camping stove. I want to stay to see what damage has been done to my own home. I’ve got my own dinghy so I’m quite safe.

I live about 200m from the river, so I do live in a flood-prone area. This is a big city, Brisbane – Australia’s third largest, and the city centre from what I last saw on TV looked like a ghost town. There were no buses, no ferries and they were talking about smashing up the river walkways.

Right now I’m looking at a car floating past my house; I can see fridges, furniture, sofas – there’s even been a report of a shark sighted.

It was a bull shark and it was spotted in a local suburban street. We do have sharks in the Brisbane River; they have obviously come over the flood barriers and come looking for food.”

 What’s causing it?

La Niña is having a disruptive impact on the eastern coast of Australia and parts of South East Asia.

The recent flooding in Queensland and the Philippines has been caused by unusually warm ocean temperatures in the western Pacific associated with a La Niña weather episode.

BBC Meteorologist, Laura Tobin, says the flooding in the south east of Brazil is unlikely to be linked to La Niña. She says La Niña is a cyclical weather phenomenon which effects mostly Pacific equatorial regions.

La Niña occurs when surface temperatures are cooler than normal in the eastern Pacific and warmer than normal in the western Pacific.

During La Niña, the cold water that pools near the coast of South America surges across the Pacific due to strengthening easterly winds. This causes a greater build up of warmer water along the eastern coast of Australia and in the South East Asia region.

The contrast in sea surface temperatures across the Pacific, as well as the contrast in air pressure, produces more rainfall in the western Pacific region.

Heavy rainfall in Sri Lanka

It is not typical that La Niña would effect the weather so far west. However BBC Meteorologist, Nina Ridge, says there is also some evidence La Niña may have had an effect on the recent rainfall in Sri Lanka.

This is because La Niña causes strong easterly winds, that could prevail across to Sri Lanka and interact with the normal north east monsoon.

Widespread impact

The World Meteorological Organization says La Niña conditions can have a widespread impact, usually associated with stronger monsoons in most parts of Asia and Australia.

The weather phenomenon has also been associated with an active hurricane season in the Atlantic.

Posted in Hazards, IGCSE, Physical Geography, Water, Weather | 1 Comment »

Lahar destroys farmlands

Posted by Lindy on January 7, 2011

5 Jan 2011

In Magelang, in Central Java on Tuesday. Lahar from the slopes of Mount Merapi has caused chaos in the area. Thousands were forced to flee their homes as lahar from the slopes of Mount Merapi inundated hundreds of houses and destroyed hundreds of hectares of agriculture fields on Monday evening.
Heavy downpours since the afternoon in the regions sent thick layers of volcanic debris down the slope of Merapi, carrying logs and volcanic rocks of up to 2 meters in diameter, destroying everything they hit along the way. The lahar destroyed at least two bridges and four houses.

The administration  had also been normalizing the stream along the river and deployed heavy equipment at the locations in case they were needed.Two excavators were deployed to help normalize the highway. However, due to the thick layers of volcanic materials, they had not yet been able to completely clear them from the road as of Tuesday afternoon.

Lahar will continue to threaten areas along the banks of the 12 rivers originating at Merapi as those rivers are still filled with thick layers of volcanic materials of up to 17 kilometers down their streams, ready to travel as heavy rain pours over the region.

Posted in Hazards, Physical Geography, Tectonics, Y9 | Leave a Comment »

Real-Time Quake Detection

Posted by alec8c on November 1, 2010

Seismologists Use Ultrasounds to Assess Quakes Faster

April 1, 2006 — Using ultrasound imaging, seismologists can now determine the epicenter and magnitude of an earthquake quake within 10 to 20 minutes, precisely imaging which fault ruptured and where the rupture went. The method could help save lives through early earthquake and tsunami warnings. By the end of this year, the U.S.G.S. will be using the method to analyze earthquakes anywhere in the world.

SAN DIEGO–The first few hours following a major earthquake are critical for seismologists, rescuers and people living in the quake zone. Now, researchers can estimate where a quake made its biggest impact within 30 minutes after a big earthquake.

It was a deadly quake that shook the world. Hundreds of thousands of people died. Kris Walker, a seismologist at Scripps Institution of Oceanography at the University of California, San Diego, says, “It actually took days before the true size of that earthquake was determined.”

If, in the first minutes, seismologists had known how large the quake was and exactly where it occurred, they’d have recognized a powerful and widespread tsunami would soon follow. “If our technique was used and had there been adequate communication infrastructure in that area, we would have been able to save a lot of lives,” Walker says.

Walker and fellow seismologist Peter Shearer have devised a method to rapidly determine how much surface shaking is generated from the epicenter of a large quake. “What we’re able to learn within 10 to 20 minutes of when the earthquake started is about which fault ruptured and where the rupture went,” Shearer says.

Earthquakes produce seismic waves. The first waves detected by seismic stations are called p-waves. Once the quake is detected, earth scientists can back track to find where the quake started. Shearer says, “You get a prediction like this, in gray, of the area that experienced the greatest surface shaking.”

This new, faster method of sizing up earthquakes can buy important time for people in the first hour following a major earthquake.

By the end of this year, the U.S. Geological Survey in Colorado will be using the back-projection method to analyze earthquakes anywhere in the world. It could become part of a worldwide warning system.



BACKGROUND: Scientists at Scripps Institute of Oceanography have devised a method to use ultrasound images to provide key information about earthquake ruptures in near or real time following a large earthquake.

HOW IT WORKS: The new method uses ultrasound imaging, a medical technique that uses high frequency sound waves and their echoes. It’s similar to how bats, whales and dolphins pinpoint locations, and to the basis for the SONAR technology used by submarines. Ultrasound waves not only let doctors see inside the body, they can provide information about the inside of an earthquake. The machine sends out high-frequency sound pulses, which bounce off objects and reflect back to a detector, which sends that data to the machine’s computer. The computer can calculate the distance between the machine and the objects by knowing the speed of sound through the earth and the time it takes for the echo to return. By measuring how the frequency of the echoes changes, scientists can also determine how fast that object is moving.

Posted in Hazards, IGCSE, Physical Geography, Solution to problems, Tectonics | Leave a Comment »

The Haiti and New Zealand Quakes: A Fair Comparison?

Posted by Lindy on September 5, 2010

At first look, the earthquake that struck Christchurch, New Zealand on Saturday was the spitting image of the one that ravaged Haiti in January.

  • Each was a powerful magnitude 7.0 quake, and
  • each occurred on a strike-slip fault
  • near a major population centre.

But the similarities end there. Reports out of Christchurch have been almost miraculous: Though the city suffered extensive damage, not a single person out of nearly 400,000 appears to have died. By contrast, the Haitian capital city of Port-au-Prince was flattened, and a quarter of a million people were killed. There remains immense suffering in the country, nearly eight months later.

There are two main reasons for this extreme contrast in events: luck, and preparedness.

First, a closer look at the two quakes reveals an important geological difference. The epicenter of the Haiti quake was just 16 miles from downtown Port-au-Prince, while in Christchurch the tremor struck more than 30 miles away.

New Zealanders were also lucky because they were at home, asleep in houses built up to the country’s stringent building codes when the quake hit at 4:35 a.m. local time. “The old buildings downtown were the ones that got beat up, which is what you’re seeing all those pictures of,” Yanev said. “There’s some luck involved that people weren’t around when parapets were falling off buildings.”

And of course, there are the building codes themselves. Straddling the boundary of the Australia and Pacific tectonic plates, New Zealand regularly experiences powerful, damaging quakes, and the government has made certain that all modern buildings are built to withstand strong shaking.

In Haiti, there are no building codes to speak of.

“There are basically four places in the world — California, Japan, Chile, and New Zealand — that are serious about earthquake design, and that’s it,” Yanev said.

Of course economic standing has a lot to do with it; New Zealand is far better off than chronically-impoverished Haiti.

Posted in Hazards, IGCSE, Physical Geography, Tectonics | Leave a Comment »

Supercomputer Reproduces a Cyclone’s Birth, May Boost Forecasting

Posted by alec8c on July 26, 2010

ScienceDaily (July 23, 2010) — As a teen in his native Taiwan, Bo-wen Shen observed helplessly as typhoon after typhoon pummeled the small island country. Without advanced forecasting systems, the storms left a trail of human loss and property destruction in their wake. Determined to find ways to stem the devastation, Shen chose a career studying tropical weather and atmospheric science.

Now a NASA-funded research scientist at the University of Maryland-College Park, Shen has employed NASA’s Pleiades supercomputer and atmospheric data to simulate tropical cyclone Nargis, which devastated Myanmar in 2008. The result is the first model to replicate the formation of the tropical cyclone five days in advance.

To save lives from the high winds, flooding, and storm surges of tropical cyclones (also known as hurricanes and typhoons), forecasters need to give as much advance warning as possible and the greatest degree of accuracy about when and where a storm will occur. In Shen’s retrospective simulation, he was able to anticipate the storm five days in advance of its birth, a critical forewarning in a region where the meteorology and monitoring of cyclones is hampered by a lack of data.

At the heart of Shen’s work is an advanced computer model that could improve our understanding of the predictability of tropical cyclones. The research team uses the model to run millions of numbers — atmospheric conditions like wind speed, temperature, and moisture — through a series of equations. This results in digital data of the cyclone’s location and atmospheric conditions that are plotted on geographical maps.

Scientists study the maps and data from the model and compare them against real observations of a past storm (like Nargis) to evaluate the model’s accuracy. The more the model reflects the actual storm results, the greater confidence researchers have that a particular model can be used to paint a picture of what the future might look like.

Posted in Fragile environments, Hazards, IGCSE, Physical Geography, Solution to problems, Weather | Leave a Comment »

Earthquake early warning toads

Posted by Lindy on April 17, 2010

Keeping an eye on the toads in your neighbourhood could give you a five-day head start in the event of massive seismic activity, says a new study published by the Zoological Society of London in the Journal of Zoology, but don’t put one in a jar on your desk just yet.

Researchers from the UK’s Open University reported that 96 percent of common male toads (Bufo bufo) in a population had abandoned their breeding site five days before a 6.3 magnitude earthquake struck L’Aquila in central Italy in 2009.

Posted in Hazards, IGCSE, Physical Geography, Tectonics, Y9 | Leave a Comment »

Haiti Day by Day 2

Posted by Lindy on January 25, 2010


A strong aftershock rocked Haiti , sending screaming people running into the streets. Some buildings already weakened by last week’s quake collapsed.  The magnitude 6.1 tremor struck west of Port-au-Prince at 0603 local time (1103 GMT).

The aftershock hit as people were still being found alive in the rubble from the original quake. They included a five-year-old boy reportedly pulled from the ruins of his home by his uncle. Earlier a 10-year-old girl and her eight-year-old brother were found.

More than 120 people altogether have been rescued by international teams.

The US announced it was sending another 4,000 sailors and marines to Haiti for the earthquake relief effort, diverting them from deployments in the Gulf and Africa.

Many victims unable to find treatment in Haiti, have crossed the border into the Dominican Republic. But  the volume of patients is so great the hospitals there are struggling to cope.

Haitian officials said the death toll from the quake was likely to be between 100,000 and 200,000, and that 75,000 bodies had already been buried in mass graves. An estimated 1.5 million are homeless.


About 400,000 survivors will be moved to tented villages outside the capital, Port-au-Prince, with 100,000 people initially being sent to 10 settlements near the suburb of Croix Des Bouquets, Interior Minister Paul Antoine Bien-Aime announced.

The International Organisation for Migration, distributing tents and plastic sheeting, warned that more permanent shelter would soon be needed by the 500,000 people living outdoors.

In a bid to deliver greater quantities of aid, the US military was operating at four airports in the region – Port-au-Prince and Jacmel in Haiti, and San Isidro and Barahona in the neighbouring Dominican Republic.

The US Coast Guard partially reopened the capital’s main sea port which was damaged in the quake. Four vessels had docked by Thursday evening.


Two people were rescued after spending 10 days under the rubble.

An 84-year-old woman and 21-year-old man were pulled out alive in Port-au-Prince, but with no further signs of life reported the Haitian government declared the rescue effort over at 1600 local time (2100 GMT).

Later a massive benefit concert was broadcast to try to raise money for victims.

The two-hour Hope for Haiti telethon featured more than 100 Hollywood and music stars.

The concert, which took place in New York, Los Angeles, London and Haiti, included Bono, Bruce Springsteen, Sting, Rihanna, Brad Pitt, Clint Eastwood, Julia Roberts and Leonardo DiCaprio. It raised  £35m ($57m)


International search teams continued their work to find survivors, despite the Haitian government calling an official end to the rescue phase, and were rewarded by pulling Wismond Exantus from the remains of the Napoli Inn Hotel 11 days after the quake.

Greek, French and US rescue teams were involved in the two-and-a-half-hour operation to bring him out.

Posted in Fragile environments, Haiti, Hazards, IGCSE, Physical Geography, Y7/8 | Leave a Comment »

The power of water!

Posted by Lindy on July 22, 2009

The Durham Grand Canyon: Flooding after heavy rain carves vast trench in farm land

By Neil Sears

Read more:
Durham picOn Friday night, it was a perfectly ordinary, perfectly flat, cornfield.

By Saturday morning, it was riven in two by a vast trench up to 30m across, 5m deep and 200 metres long.

The enormous gully  –  so big that locals have called it ‘the Grand Canyon of Durham’  –  is believed to have been formed in a matter of minutes when millions of gallons of floodwater from surrounding farmland suddenly tore through the soil towards the River Wear.

Simultaneously, the high waters of the Wear had broken the banks at exactly the same point  –  and in an instant, a new tributary to the river was formed. Luckily, no buildings were near enough to be affected.

Durham mapNow the floodwater has drained away and the river has returned to its normal level, an almost empty canyon remains, with just a trickle of water at the bottom.

It is an extraordinary illustration of the power of nature  –  and shows that enough water, flowing with enough force, doesn’t need decades to carve a path through the earth.

In fact, it is estimated that the water carried into the river up to 12,000 cubic metres of soil, weighing 15,000 tons, the volume of 25 swimming pools.

Durham experienced 80mm of rain in 24 hours, ten times the average, helping to create the new feature in a field belonging to Houghall agricultural college in the village of Shincliffe.

Pete Whitfield, from the college, discovered the canyon on Saturday morning when he rushed to work to sort out the flooding problems, which were so bad several pigs were drowned.

He was early enough on the scene to see the water thundering into it from the field.

‘I heard this rushing like Niagara Falls,’ he said. ‘And I could see this water wearing away the land. The field was perfectly flat 25 acres before. Now there’s only about 18 acres left.

‘It’s an amazing phenomenon, but I estimate it’s the result of water from up to 120 acres of flooded land.’

Posted in Hazards, IGCSE, Physical Geography, Water, Weather, Y7/8 | Leave a Comment »

Town Ignored warning of Earthquake

Posted by Lindy on April 7, 2009

It has always been difficult to tell when an earthquake will hit.

But there had been earth tremors since mid-January in and around L’Aquila in Central Italy.

Giampaulo Giuliani worked at a physicist .  He claimed to have detected radon gas emissions which could only be released under intense pressure. However, the local mayor charged him with scaremongering which meant that he could no longer speak out about his fears of an earthquake.

But on Sunday, Giampaulo be came even more worried when his readings indicated immanent disaster. But he could do nothing with the information because of the injunction on him.

Since the last post the death toll has risen to 179.

Posted in Fragile environments, Hazards, IGCSE, Physical Geography | Leave a Comment »