What is a tsunami?

TOKYO: A once-exotic word that has now entered the everyday lexicon, a tsunami refers to a shock of water that spreads through the sea, usually after a sub-sea floor quake.

A section of seabed is thrust up or driven down by violent movement of the Earth”s crust.

The rift displaces vast quantities of water that move as waves, able to cover enormous distances over open water, sometimes at the speed of a jet plane.

An 8.9-magnitude quake off Japan”s northern coast on Friday generated a 10-metre (33 feet) tsunami that picked up ships and dashed them into coastal towns.

Buildings and vehicles were carried away as the huge wall of water swept inland.

The word “tsunami” comes from the Japanese words for “harbour” and “wave”.

At their point of generation, tsunamis have a relatively small wave height, with peaks far apart.

As the waves approach the shore they are compressed by the shelving of the sea floor, reducing the distance between the peaks and vastly increasing the height.

To those on the shore, the first sign of something amiss can be the retreat of the sea, which is followed by the arrival of large waves.

“The sea was driven back, and its waters flowed away to such an extent that the deep seabed was laid bare and many kinds of sea creatures could be seen,” wrote Roman historian Ammianus Marcellus, awed at a tsunami that struck the then-thriving port of Alexandria in 365 AD.

“Huge masses of water flowed back when least expected, and now overwhelmed and killed many thousands of people… Some great ships were hurled by the fury of the waves onto the rooftops, and others were thrown up to two miles (three kilometres) from the shore.”

Several factors determine the height and destructiveness of a tsunami.

They include the size of the quake, the volume of displaced water, the topography of the sea floor as the waves race to the coast and whether there are natural obstacles that dampen the shock.

Destruction of protective mangroves and coral reefs and the building of homes or hotels on exposed beaches are fingered as leading causes of high death tolls from tsunamis.

Large quakes are the main drivers of tsunamis, but the phenomenon can also be sparked by other cataclysmic events, such as volcanic eruptions and even landslides.

In 1883, a volcano shattered the Pacific island of Krakatoa, causing a blast so loud that it could be heard 4,500 kilometres away, followed by a tsunami that killed some 30,000 people.

The tsunami of December 2004 in the Indian Ocean was caused by a monstrous 9.1-magnitude earthquake off the Indonesian island of Sumatra.

It released energy equivalent to 23,000 of the atomic bombs dropped on Hiroshima, according to the US trendpk.comlogical Survey (USGS). Some 220,000 people in 11 nations were killed, many of them thousands of kilometres from the epicentre.

The Pacific Ocean is particularly prone to earthquakes and therefore to tsunamis.

But research has found that, over the millennia, tsunamis have occurred in many parts of the world, including the Atlantic and Mediterranean. A global monitoring network, overseen by the UN, has been set in place to alert areas at risk.

Nawaz says won’t accept RGST Bill

Nawaz Sharif on Wednesday resolved to make PML-N a revolutionary party.

Addressing a public gathering at Sumundri, Nawaz said that corruption in Hajj arrangements is an unpardonable mistake. It is the height of corruption in our country; the federal minister himself admitted the irregularities, he lamented. Referring to RGST, he said, The government should eliminate corruption prior to imposing the RGST Bill; We will not accept this Bill.Nawaz maintained that the government would not be in need of loans, if it spends the money being collected through tax judicially. He denied the allegation leveled on him by Wikileaks, saying that Musharraf dubbed him a hijacker wrongly. Do I look like a highjacker?, the PML-N chief asked the audience. He blamed the incumbent government for the prevalent power shortage.

11 killed, 34 injured in Baghdad suicide attack

BAGHDAD: A suicide truck bomber killed at least 11 people and wounded 34 others on Wednesday in an attack on a police station in the Iraqi capital, security sources said.

The blast took place in Baghdad’s northern Qahira district, an Interior Ministry source and police sources said.

The bomber blew the truck up near the police station, causing part of the building to collapse and severely damaging surrounding houses, the Interior Ministry source said.

Iraq is on high alert for insurgent attacks after an inconclusive March election produced no clear winner and left the country adrift in political uncertainty at a time when U.S. troops are preparing to end combat operations on Aug. 31.

Overall violence in Iraq has dropped sharply since the height of sectarian carnage in 2006-07. But bombings and killings take place daily, suggesting insurgents are

Leadville 100

Mountain bike race Leadville 100 is now under way. And began at 6:30 am local time (9:30 EST) in Leadville, Colorado, with more than 1500 runners. One rider, who missed this year? Star Lance Armstrong.

And was scheduled Armstrong to race in the 100 Leadville, but pulled out earlier this week because of an injury suffered in the Tour de France.

100 Leadville race is actually 104 miles long, and go from starting in the height of 10,500 feet to 12600 feet and back again.

In 2009, Armstrong won the race in 100 Leadville. It is certainly a disappointment that he would not ride this year, but that field is strong, the six-times 100 Leadville Dave winner Wiens, Matt Shriver, who placed third in 2009, followed by teammate Armstrong, Levy, and hundreds and hundreds.

3 injured in Spain running of bulls

PAMPLONA, Spain: A man was gored in an arm and two others were injured in a tense, fast-paced penultimate running of the bulls at Spain’s San Fermin festival Tuesday, officials said.

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3 injured in Spain running of bulls

Study: Obese men face higher death risk

STOCKHOLM: New research suggests that men who are obese by age 20 die eight years earlier on average than their non-obese peers.

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Study: Obese men face higher death risk

EU: Estonia can join euro next year

BRUSSELS: European Union nations on Tuesday gave final approval for Estonia to become the 17th country to join the euro, a boost for the tiny Baltic country and a sign of confidence in the troubled currency union.

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EU: Estonia can join euro next year

SAfrican Olympic committee vows to bid for 2020

JOHANNESBURG: South Africa says it will bid to host the 2020 Olympics.

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SAfrican Olympic committee vows to bid for 2020

Nepal parliament to elect new PM on July 21

KATMANDU: Nepal’s president has asked parliament to choose a new prime minister by simple majority vote, officials said Tuesday, in an attempt to break the Himalayan nation’s political gridlock.

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Nepal parliament to elect new PM on July 21

High School star Efron graduates to producer

LOS ANGELES: Former High School Musical star Zac Efron, who successfully moved into adult fare last year with 17 Again, is quietly establishing his credentials as a Hollywood producer.

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High School star Efron graduates to producer

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