Can earthquakes be predicted?

Think scientists are close to being able to predict earthquakes? Think again. The magnitude 9 quake off the Indonesian island of Sumatra that triggered December's devastating tsunami, was a potent reminder that while it is easy to say where big quakes will happen, pinning it down to a day, a week or even a decade has proved impossible, said US quake experts.
It is a question in point, is there any way to control or reduce the intensity of expected earthquakes? The answer is no, it is impossible at present, but quakes can sometimes be predicted in future to warn the populace.
Geologists have discovered that certain warnings occur. When the process starts, the strain 'in a fault increases and the rock approaches its breaking point, myriads of microscopic cracks appear in it, which cause the rock to swell, tilting or uplifting the ground above it.
Some scientists believe that this phenomena known as dilatancy, causes several interrelated things to happen: seismic waves slow down as they pass through the region; the pressure squeezes water out of the rock, thus raising nearby water levels; the rock ' becomes more resistant to electric currents; and an increased quantity of rare radon gas is released.
Shortly before the quake, water seeps back into the micro-cracks and all things return to normal.
The return of the water also weakens the dilated rock along the fault, producing a swarm of small foreshocks which build up rapidly. Then the tremors abruptly cease, the earth becomes ominously quiet, until- suddenly-the fault splits in a giant rupture, the sides jerk convulsively past or over each other, shaking the earth. Often there are aftershocks that can be almost as violent.
Some claim that animals know when a quake is coming. The Chinese, who have recorded such phenomena for nearly 3000 years, report that shortly before a big quake rats flee from buildings, and horses and pigs run around in a frenzy.
The reason for these eccentricities is not known. Perhaps animals can feel vibrations, hear sounds, smell radon, or sense changes in electrical fields that are undetectable to humans.
By studying precursors, geophysicists of the University of Texas were able to forecast a sizeable earthquake in Oaxaca, Mexico, two years before it occurred in 1978, and others in New York and California have predicted smaller local quakes almost to their exact day and location.
According to a study China was the first to achieve the greatest success in earthquake prediction in 1975, where 10,000 professionals, aided by some 100,000 amateur seismologists, watched for earthquake symptoms in 5000 locations. Around the city of Haicheng, Manchuria, they noted slight changes in tilt and electrical conductivity, variations in the levels and the radon content of well water, and a rapid build-up of small tremors.
When the tremors suddenly terminated on February 4, 1975, authorities ordered the evacuation of the city. Five and one-half hours later Haicheng was rocked by a temblor that destroyed or severely damaged 90 percent of the city's structures.
After this achievement some American geologists announced enthusiastically that earthquake prediction can now practically be accomplished. But their claim failed when just 18 months later, a big quake occurred without warning at Tangshan, China, that claimed 750,000 lives. Over a two-year period, China made 31 predictions of which 18 were accurate, seven doubtful and six were absolutely wrong. The problem is that no two quakes are preceded by exactly the same set of warnings, and even these symptoms can be misleading.
Despite all these facts, scientists are certain that, with more and better data, earthquake prediction will become ever more reliable. The US Geological Survey have installed over 1000 seismic measuring devices in trouble spots to keep track of what's happening in the crust of the earth. "Within ten years or so we should be able to predict earthquakes at least as accurately as the weather," leading American geologists have stated.
EARLY WARNING SYSTEM: Delegates from 11 nations hit by the December 26 tsunami including Bangladesh, India, Indonesia, Kenya, Malaysia, Maldives, Myanmar, Seychelles, Sri Lanka, Tanzania and Thailand met in a seminar at Tokyo last month to learn how earthquake-prone Japan operates an early warning system. Japan will provide examples of tsunami disaster reduction based on its experiences.
Japan hit by twenty percent of the world's major earthquakes, has one of the world's most advanced systems to predict tsunamis
Japan is one of the main countries, along with Australia, France, Germany and the United States, offering to share its technology to build an Indian Ocean tsunami warning system which the UN hopes to have in place by mid-2006, with a global system a year afterward.
The failure of an alert system in the Indian Ocean region contributed to the catastrophic death toll as many victims were swept from coastlines hours after the 9.0 magnitude quake was recorded near Sumatra. One of the worst natural disasters in modern history, tsunami killed more than 289,000 people by the giant waves in 11 countries.
DEATH TOLL: The Indian Ocean earthquake and tsunami on December 26 killed at least 123,071 people in Aceh province on Sumatra island, according to the Indonesian government.
A total of 113,937 were missing, and nearly 401,000 were made homeless, the latest government data show.
Elsewhere, about 38,000 people were killed in Sri Lanka, 11,000 in India and 5,400 in Thailand. People in Malaysia, the Maldives, Myanmar, Bangladesh and East Africa also died.
Rescue teams have nearly finished their work in tsunami-hit areas. But the real death toll may never be known.
The discrepancy may reflect the difficulties involved in counting the dead where whole villages were swept out to sea and most of the bodies will never be found.
But it may also reflect an embarrassing and sensitive fact that many of the victims were illegal settlers on islands supposedly reserved for indigenous tribes.
TECHNICAL MAPS: Technicians would have to draft new technical maps with the changes occurring in geographical positions.
According to researchers it is common for land to move by one centimetre a year. And around one month after the earthquake, Bangkok had moved horizontally south-westwards by about nine centimetres, and Phuket moved horizontally by about 32 centimetres south-westwards as well.
Bangkok has shifted nine centimetres (3.5 inches) because of the December 26 earthquake. The tourist island of Phuket also moved 32 centimetres (12.6 inches) since the quake, said the Chulalongkorn University researchers, who used Global Positioning System (GPS) satellites to measure the shifts during a January 20-24 survey.
Researchers in Malaysia had found that the country has been moving westwards by one centimetre every week since the quake, and that a similar phenomenon was probably happening in southern Thailand.
The Indian Ocean archipelago has 1,192 tiny coral islands scattered some 850 kilometres (550 miles) at sea level across the equator.
The entire Maldives was submerged for 15 minutes following the December 26 tsunamis.
Only 199 out of the 1,192 islands in the archipelago are inhabited, and 13 of them were made "uninhabitable" by the sea surge. Eighty-seven islands are tourist resorts.
Only four islands in Maldives have a population of more than 5,000 and another 119 have less than 1,000 people.
Same is the case in Iran where a quake destroyed several villages on 22 February, 2005 killing almost 400 people, injuring hundreds. There were no predictions of the quake, same as happened in Bam just over a year ago where 30,000 people were killed in December 2003 when a quake measuring 6.7 struck.
The US Geological Survey said the earthquake measured 6.4 on the Richter scale and was located 60 kilometers north north-west of the city of Kerman.
The region hit by this quake is some 200 kilometres north-west of Bam.
HOW QUAKES OCCUR: "Over 2000 times a day, the world is shaken by earthquakes caused by the jostling or collision of the moving, 50-mile-thick crystal plates that cover the surface of our planet. More than 95 percent of the tremors are too weak to be felt by anything but sensitive seismometers." About 15 times a year, earthquakes of great violence rip through the earth, sometimes causing it to ring like a bell, said scientists.
The most frequently strike in three areas: where ocean plates are thrusting under land plates, as is happening along the coasts of Alaska and Central and South America, and the island arcs of Japan, Indonesia and the Caribbean; where the plates are grinding past each other, as in California and Turkey; and where continents are running into each other, as in China, Iran, arid the countries of the Balkans and eastern Mediterranean, which are slowly crumbling under the pressure exerted by northward-moving India, Arabia and Africa, respectively.
The destruction caused by such quakes can be horrifying, resulting in the loss of thousand of lives. About 830,000 people killed in China in 300,000 in India in 1237, 143,000 in Japan in 1923. The worst natural catastrophe in modern times occurred when a giant quake shattered the city of Tangshan, China, leaving an estimated 750,000 people dead, 780,000 injured, 500,000 homeless, destroying or severely damaging almost every multi-story building in the city.
According to geologists, great earthquakes may also occur deep in the hearts of plates.
Passing Plates. The causes of quakes in the north-east, south-east Mississippi Valley, thousands of miles from the nearest plate boundaries, are still a mystery. Fortunately, big ones are infrequent in any one area, occurring several centuries apart. Precautions must be taken, new building major dams, bridges and other public works should be reinforced against possible quakes.