Saturday, April 3, 2010

Hydrosphere at work(lower congo river)




The Congo River is a place of superlatives; it is the world’s second largest river basin, draining an area the size of Europe; so immense that its source waters in the highlands of east Africa take more than six months to exit into the Atlantic Ocean, some 2,900 miles (4,670 km) to the west. The river and its tributaries represent over 9,000 miles (14,500 km) of navigable passage across central Africa, and provide food and livelihoods for the 30 million people who live in this vast region.

Big barrier

This massive river also forms one of the largest biogeographical barriers in Africa.

For example, our closest relatives, the chimps (Pan troglodytes) and the bonobos (Pan paniscus) are separated by the Congo River; chimps are found only to the north and bonobos only to the south.

Many other animals show a similar pattern of distribution; the Congo River has clearly played an important role in sorting African biogeography. Nevertheless, we know surprisingly little about its history.

But we do know that the river has not always looked the way it does today. Geologists estimate that perhaps as recently as half a million years ago, the Congo was a large lake or series of lakes with no outflow to the Atlantic Ocean. At some point the Congo breached a high plateau in the region of present day Malebo Pool — a peculiar place where the river expands into an enormous 14-mile-wide (22.5 km-wide) pool. In Conrad’s day this strange place was known as Stanley Pool, after the explorer and emissary of the now infamous Belgian King Leopold II.

Most of the great inland lake was drained and a "new" river cascaded down through the gorges of the Crystal Mountain region, dropping about 920 feet (280 m) over 220 miles (350 km) to reach the Atlantic. Today, some of the most spectacular rapids on Earth and a rich endemic fish fauna are found in the river as it flows between Pool Malebo and the Atlantic. These fishes are termed lower Congo "endemics" because they occur only in this short stretch of the river. It is this region, called the lower Congo River rapids, with its spectacular array of rapids, pools and runs, that is our study area.

Isolated stretch

The extraordinary hydrology of the lower Congo appears to have isolated it from the remainder of the river basin and this short stretch represents a model system for exploring patterns of species richness and local endemism, while perhaps also holding the key to understanding the origin and age of the entire Congo River itself. The fishes found only in the lower Congo rapids can only have evolved after the formation of the rapids themselves, and those rapids formed when the proto-lake Congo drained to the Atlantic.

By studying those fishes, we hope to get a handle on when the Congo took its present-day form.

But studying those fishes is no easy task; the area is remote and rugged, roads are few and far between and when present are often impassible. What’s more, few reliable maps are available to aid our search for access to the river. But unlike Stanley and other earlier travelers in the region, we have the luxury of remotely sensed satellite imagery to help us locate possible access points by road and by foot that can take us to river collecting sites and places to set up camp – large sand banks and bars that are scattered between huge rocky outcrops along the river, make idyllic camp sites from where we can cautiously venture out in local piroges (huge canoes carved out of tree trunks).

Analysis of remotely sensed data also gives us an invaluable birds-eye view of the numerous macrohabitats and channel features that characterize this hydrologically complex stretch of river. Using the latest remote sensing technologies, and with much on-the-ground sampling and analysis, we are beginning to get a much clearer picture of just how the hydrology of the river has played a major role in isolating fish populations. We have mapped rapids and can begin to measure their power, we have found evidence of extremely deep underwater canyons, we have found blind fishes and fishes with bizarre anatomical features and adaptations to life in fast waters, and we have discovered numerous species new to science.

Yet working in this region is difficult. Catching fish in such turbulent water flowing at extreme velocities over treacherous rocks is a bit like trying to "catch" a needle in a haystack — we rely heavily on the experience and ingenious skill of the local people who have been fishing these difficult waters for millennia.

But despite how much we are learning and documenting, our project has only begun to scratch the surface of this extraordinary place — we are certainly leaving a great deal for our Congolese colleagues and students to continue to explore.

Personal Response:
When we talk about hydrology, we often assume that it only involves formation of water features such as ox-bow lakes or the meandering of the rivers. Though often true, however, unknown to many, these progressive formations of the river and it features often affect the animal population that lives in the water.
After the formation of the lower congo river, the fast currents of the
water form a impenetrable wall which isolated populations of fishes.This isolation thus prevents fish populations to be able to cross breed. As such, mutation of the similar fish species could be observed at different parts of the river.
In addition, as the river pose as a relatively harsh environment to live in,fishes evolved so as so survive in the river. Some fishes, like the tiger fish evolved into such, so as to overcome the fish currents as well as to hunt for prey within the water of the lower congo.
In this note, geography often affect us in more ways than we can imagine.


What did you know! :3

The massive 8.8 earthquake that struck Chile may have changed the entire Earth's rotation and shortened the length of days on our planet, a NASA scientist said Monday.

The quake, the seventh strongest earthquake in recorded history, hit Chile Saturday and should have shortened the length of an Earth day by 1.26 microseconds, according to research scientist Richard Gross at NASA's Jet Propulsion Laboratory in Pasadena, Calif. One microsecond is one-millionth of a second long.

“This change should be permanent,” Gross told SPACE.com today. There is a chance the Earth’s rotation could relax over time, but it is too early to tell, he said.

The computer model used by Gross and his colleagues to determine the effects of theChile earthquake effect also found that it should have moved Earth's figure axis by about 3 inches (8 cm or 27 milliarcseconds).

"Perhaps more impressive is how much the quake shifted Earth's axis," NASA officials said in a Monday update.

The Earth's figure axis is not the same as its north-south axis, which it spins around once every day at a speed of about 1,000 mph (1,604 kph).

The figure axis is the axis around which the Earth's mass is balanced. It is offset from the Earth's north-south axis by about 33 feet (10 meters).

Strong earthquakes have altered Earth's days and its axis in the past. The 9.1 Sumatran earthquake in 2004, which set off a deadly tsunami, should have shortened Earth's days by 6.8 microseconds and shifted its axis by about 2.76 inches (7 cm, or 2.32 milliarcseconds).

One Earth day is about 24 hours, or 86,400 seconds, long. Over the course of a year, the length of a day normally changes gradually by about one millisecond, which is 1,000 microseconds.

That variation is due to seasonal variations in the Earth’s ocean currents and the atmosphere’s jet stream, Gross said. As the jet stream shifts southward during the winter months in the Earth’s northern hemisphere, the length of the day gradually changes, he said.

In the past, Gross has said that Earth’s rotation slows down slightly in during the northern winter months, then picks back up in the northern summer.

The Chile earthquake was much smaller than the Sumatran temblor, but its effects on the Earth still have an impact because of its location. Its epicenter was located in the Earth's mid-latitudes rather than near the equator like the Sumatran event.

Gross compared the Sumatran event to a figure skater drawing her arms inward during a spin to turn faster on the ice. Since the Sumatran quake was closer to the Earth’s equator, its day-shortening effect is stronger than the Chile temblor, he said.

But the fault responsible for the 2010 Chile quake also slices through Earth at a steeper angle than the Sumatran quake's fault, NASA scientists said.

"This makes the Chile fault more effective in moving Earth's mass vertically and hence more effective in shifting Earth's figure axis," NASA officials said.

Gross said his findings are based on early data available on the Chile earthquake. He is confident in the computer model’s accuracy, with only slight tweaks expected to be required, he said.

The Chile earthquake has killed more than 700 people and caused widespread devastation in the South American country.

Several major telescopes in Chile's Atacama Desert have escaped damage, according to the European Southern Observatory managing them.

A salt-measuring NASA satellite instrument destined to be installed on an Argentinean satellite was also undamaged in the earthquake, JPL officials said.

Source: 03 April 2010, http://www.msnbc.msn.com/id/35662192/ns/technology_and_science-space/

Personal response:

People often think of earthquake as a disaster which only affects us financially and in terms of casualties and loss of lives. However, apparantly, its not only in those aspects that we are affected. Through major disasters, the axis of the planet is realigned. This in turn causes the days to be shorter. In this sense, who said earthquakes are all bad. :)


The difference

Chile Earthquake

source: 03 April 2010, http://www.huffingtonpost.com/2010/02/27/chile-haiti-earthquake-co_n_479705.html

PORT-AU-PRINCE, Haiti — The earthquake in Chile was far stronger than the one that struck Haiti last month – yet the death toll in this Caribbean nation is magnitudes higher.The reasons are simple.Chile is wealthier and infinitely better prepared, with strict building codes, robust emergency response and a long history of handling seismic catastrophes. No living Haitian had experienced a quake at home when the Jan. 12 disaster crumbled their poorly constructed buildings.And Chile was relatively lucky this time.

Saturday's quake was centered offshore an estimated 21 miles (34 kilometers) underground in a relatively unpopulated area while Haiti's tectonic mayhem struck closer to the surface – about 8 miles (13 kilometers) – and right on the edge of Port-au-Prince, factors that increased its destructiveness."Earthquakes don't kill – they don't create damage – if there's nothing to damage," said Eric Calais, a Purdue University geophysicist studying the Haiti quake.

The U.S. Geological Survey says eight Haitian cities and towns – including this capital of 3 million – suffered "violent" to "extreme" shaking in last month's 7-magnitude quake, which Haiti's government estimates killed some 220,000 people. Chile's death toll was in the hundreds.By contrast, no Chilean urban area suffered more than "severe" shaking – the third most serious level – Saturday in its 8.8-magnitude disaster, by USGS measure. The quake was centered 200 miles (325 kms) away from Chile's capital and largest city, Santiago.

In terms of energy released at the epicenter, the Chilean quake was 501 times stronger. But energy dissipates rather quickly as distances grow from epicenters – and the ground beneath Port-au-Prince is less stable by comparison and "shakes like jelly," says University of Miami geologist Tim Dixon.Survivors of Haiti's quake described abject panic – much of it well-founded as buildings imploded around them. Many Haitians grabbed cement pillars only to watch them crumble in their hands. Haitians were not schooled in how to react – by sheltering under tables and door frames, and away from glass windows.

Chileans, on the other hand, have homes and offices built to ride out quakes, their steel skeletons designed to sway with seismic waves rather than resist them."When you look at the architecture in Chile you see buildings that have damage, but not the complete pancaking that you've got in Haiti," said Cameron Sinclair, executive director of Architecture for Humanity, a 10-year-old nonprofit that has helped people in 36 countries rebuild after disasters.Sinclair said he has architect colleagues in Chile who have built thousands of low-income housing structures to be earthquake resistant.In Haiti, by contrast, there is no building code.Patrick Midy, a leading Haitian architect, said he knew of only three earthquake-resistant buildings in the Western Hemisphere's poorest country.

Sinclair's San Francisco-based organization received 400 requests for help the day after the Haiti quake but he said it had yet to receive a single request for help for Chile."On a per-capita basis, Chile has more world-renowned seismologists and earthquake engineers than anywhere else," said Brian E. Tucker, president of GeoHazards International, a nonprofit organization based in Palo Alto, California.Their advice is heeded by the government in Latin America's wealthiest nation, getting built not just into architects' blueprints and building codes but also into government contingency planning."The fact that the president (Michelle Bachelet) was out giving minute-to-minute reports a few hours after the quake in the middle of the night gives you an indication of their disaster response," said Sinclair.

Most Haitians didn't know whether their president, Rene Preval, was alive or dead for at least a day after the quake. The National Palace and his residence – like most government buildings – had collapsed.Haiti's TV, cell phone networks and radio stations were knocked off the air by the seismic jolt.

Col. Hugo Rodriguez, commander of the Chilean aviation unit attached to the U.N. peacekeeping force in Haiti, waited anxiously Saturday with his troops for word from loved ones at home.He said he knew his family was OK and expressed confidence that Chile would ride out the disaster."We are organized and prepared to deal with a crisis, particularly a natural disaster," Rodriguez said. "Chile is a country where there are a lot of natural disasters."

Calais, the geologist, noted that frequent seismic activity is as common to Chile as it is to the rest of the Andean ridge. Chile experienced the strongest earthquake on record in 1960, and Saturday's quake was the nation's third of over magnitude-8.7.

"It's quite likely that every person there has felt a major earthquake in their lifetime," he said, "whereas the last one to hit Port-au-Prince was 250 years ago.""So who remembers?"

On Port-au-Prince's streets Saturday, many people had not heard of Chile's quake. More than half a million are homeless, most still lack electricity and are preoccupied about trying to get enough to eat.Fanfan Bozot, a 32-year-old reggae singer having lunch with a friend, could only shake his head at his government's reliance on international relief to distribute food and water."Chile has a responsible government," he said, waving his hand in disgust. "Our government is incompetent."

Source: 03 April 2010, http://www.huffingtonpost.com/2010/02/27/chile-haiti-earthquake-co_n_479705.html


Personal Response:

The earthquake that affected Haiti was of magnitude 7.0 while Chile was struck by an earthquake of 8.8. However, the casualty rates and that of losses were higher in Haiti than in Chile though the magnitude is significantly higher in Chile. This difference in losses can be explained with different reasons.

Firstly, the designs of the buildings. In Chile, the structures were designed to 'sway' with the earthquake and thus is more resistant to being destroyed as compared to the buildings in Haiti which "pancaked" when the earthquake happened. This is important as many lives could be loss due to crumbling buildings and falling debris.

Secondly, the readiness of the people to react to the earthquakes. In Chile where earthquakes are prone, citizen know what to do when an earthquake happens like hide under a table and avoid glass windows. However, in Haiti, where it is unlikely for anyone to have experienced an earthquake before to be educated in these things to do in an event of an earthquake. As such, the possibility for death and injuries would be higher in Haiti.



Tuesday, March 30, 2010

Chile's earthquake


A massive earthquake has hit the coast of Chile, killing more than 100 people, flattening buildings and triggering a tsunami.

The 8.8-magnitude quake shook the country for a minute and half at 3:34am (6:34am GMT) today.

A tsunami warning has been extended across 53 countries, including most of Central and South America and as far as Australia and Antarctica.

The wave has already caused serious damage to the sparsely populated Juan Fernandez islands, off the Santiago coast, and is now travelling across the ocean at several hundred km per hour.

People in the Galapagos and on Easter Island have already taken refuge, while the US has started evacuating the shoreline communities of Hawaii.

At least 122 have been killed in the quake, according to Chile’s national emergency office.

President Michelle Bachelet has declared a “state of catastrophe” in the country. Calling for calm from an emergency response centre, the outgoing president said: “We have had a huge earthquake, with some aftershocks.

“Despite this, the system is functioning. People should remain calm. We’re doing everything we can with all the forces we have. Any information we will share immediately.”

The quake hit near the town of Maule, 200 miles southwest of Santiago, at a depth of 22 miles underground.

The epicentre was just 70 miles from Concepcion, Chile’s second-largest city, where more than 200,000 people live along the Bio Bio river.

TV Chile reported that a 15-storey building collapsed in the city, while other buildings caught fire and massive cracks opened up in the streets and bridges.

Cars turned upside down lay scattered across one damaged bridge.

Dozens of people were seen roaming through the streets, some wheeling suitcases behind them and others gathering around open fires to keep warm.

Many are terrified by the powerful aftershocks and are desperately trying to call friends and family.

The telephone and power lines are down in much of central Chile, making it difficult to assess the full extent of the damage close to the epicentre.

Chile is the world’s top copper producing country and the quake halted operations at two major mines.

“Never in my life have I experienced a quake like this, it’s like the end of the world,” one man told local television from the city of Temuco, where the quake

forced staff to evacuate the regional hospital.

Santiago airport has been shut down and will remain closed for at least the next 24 hours after the passenger terminal suffered major damage.

In Talca, just 65 miles, from the epicentre, neighbours pulled at least five people from the rubble while emergency workers, themselves disoriented, asked for information from reporters.

The Foreign Office has updated its travel information for people planning to go to Chile, saying: “The Foreign and Commonwealth Office is in contact with our embassy in Santiago in order to establish the facts on the ground.

“Communications are sporadic. We will update this advice over the next few hours.”

The Chilean ambassador, Rafael Moreno, said he was trying to help worried British-based relatives make contact with their families in the country.

In the coastal city of Vina del Mar, the earthquake struck just as people were leaving a disco, Julio Alvarez told a local radio station. “It was very bad, people were screaming, some people were running, others appeared paralyzed. I was one of them.”

Several big aftershocks later hit the south-central region, including ones measuring 6.9, 6.2 and 5.6.

The earthquake was caused by the floor of the Pacific being pushed below South American land mass.

This sudden jerking of the sea-floor displaced water and triggered a tsunami, which is now crossing the ocean at a speed of a jet plane.

The Pacific Tsunami Warning Center issued a warning for Chile and Peru, and a less-urgent tsunami watch for Ecuador, Colombia, Panama, Costa Rica and Antarctica.

A spokesman said: "Sea level readings indicate a tsunami was generated.

"It may have been destructive along coasts near the earthquake epicentre and could also be a threat to more distant coasts."

All Pacific islands including the Hawaii and the Easter Islands have also received warnings.

US Civil Defense officials in Hawaii said they were preparing to start evacuations from shoreline communities.

The Joint Australian Tsunami Warning Center also warned of a “potential tsunami threat to New South Wales state, Queensland state, Lord Howe Island and Norfolk Island".

Any potential wave would not hit Australia until Sunday morning local time, it added.

On the Easter Islands people are now seeking higher ground before the wave strikes.

Earthquakes are relatively common in Chile, which is part of the pacific “ring-of-fire” tectonic-plate boundary, and many buildings are built to withstand tremors.

The largest earthquake ever recorded struck the same region on May 22, 1960. The magnitude-9.5 quake killed 1,655 people and left two million homeless.

The tsunami that it caused killed people in Hawaii, Japan and the Philippines and caused damage to the US West Coast

source: 30 March 2010 http://www.timesonline.co.uk/tol/news/world/us_and_americas/article7043637.ece

Personal Responses:

The earthquake of magnitude 8.8 devastated Chile at 3.34 in the morning. This is the time where most people are in bed and resting at home. However, during the earthquake that lasted for one and a half minutes,only around 122 people were killed. For a disaster of such magnitude, i feel that 122 death is considered a really small amount. This relatively low death rate is due to the fact that the buildings were build to withstand earthquakes. This directly brought down the death rate significantly.

Personally, i felt that these earthquake proof designs were only possible because of Chile's economic wealth(Chile is the world top copper producer). In addition, Chile is also efficient in the sense that they also have protocols in place in the event of any such major disaster, which took effect after the earthquake happened.This in turn help reduce panic and chaos, and quickly put the situation under control. To top it off, due to the technological advancements of the nation, they predicted that a tsunami was generated and issued a tsunami warning to those possible affected areas which could also directly reduce lost of lives.

Ultimately, the ability to predict these natural disaster or to mitigate it, lies in the hand of those that can afford it.