Man exists on this earth subject to geological consent, which can be withdrawn at any time.

Source of Tsunamis as explained by Northwestern geology professors

On the morning of Dec. 26, a 30-foot tsunami crashed into the coasts of Indonesia, Thailand, Sri Lanka and southern India at the speed of a jet plane.

But what caused the deadly waves? Northwestern geology professors are making sure students understand the science behind the tragedy.

Geology Prof. Emile Okal is hosting a lecture, titled "The Sumatra Disaster: Questions and Answers with a Tsunami Scientist" Saturday at 5 p.m. in Harris Hall.

"I feel it´s part of my duty as a professor to share my knowledge and expertise with the Northwestern community at large," Okal said.

Okal said he hopes to tell students a few stories about how being educated about natural disasters can help save lives and then open the floor to questions.

Geology Prof. Seth Stein included a lecture on what caused the Indian Ocean tsunami in his "Geology 202" class on Monday. Stein explained to students what caused the tsunami and why it was so deadly.

Stein said tsunamis are caused by earthquakes on the ocean floor, which in turn are caused by a shift in Earth´s tectonic plates along fault lines.

The Indian Ocean earthquake that caused the December tsunami occurred along the Sunda trench, between the India tectonic plate and the Burma tectonic plate. Stein said although the plates usually move only about 50 millimeters every year, about 200 years of accumulated motion along the fault line caused it to move by 30 feet.

"Think of taking a 700-mile-long stretch of sea floor and pushing it 30 feet," Stein said.

The drastic move caused the ocean floor to collapse in some places and rise in others, displacing a large amount of water and generating waves, or tsunamis, Stein said.

"The thing travels at about the speed of a jet plane across the ocean, but in the deep ocean, its amplitude is small," Stein said. "If you were in a boat you would never even notice it, but as the wave approaches shore, it slows up, and its amplitude builds up to conserve energy."

Stein said the nature of the tsunami gave it several destructive qualities. He said most people probably drowned when they were swept up by the powerful wave, but others were killed by debris. He also said the tsunami flooded coastal water wells with salt water, depleting stores of fresh water. Finally, the cesspools created by the stagnant salt water will become mosquito breeding grounds and bring the threat of water- and insect-borne diseases.

Stein also addressed one of the questions that has victims most distressed: "Why wasn´t anyone warned?"

He said other areas of the world track tsunamis by evaluating seismic waves, which travel much faster than the tsunami and can serve as warnings. But because tsunamis in the Indian Ocean are rare, neighboring countries failed to produce a warning system.

"This was just an organizational failure," Stein said. "The idea of creating an Indian Ocean tsunami system had been floating around for a while, but it never reached the top of any country´s priority list."

Both Stein and Okal agree that increased education about tsunamis may help prevent future disasters.

"When people for one reason or another are more aware of the nature of such dangers, lives are saved," said Okal.

Reach Julia Neyman at [email protected].

Quick facts:

Tsunami is a Japanese word that means "harbor wave."

Tsunamis are caused by earthquakes on the ocean floor, which are in turn
caused by a shift in Earth´s tectonic plates along fault lines.

These shifts cause the ocean floor to collapse in some places and rise in
others, displacing a large amount of water and generating large waves.



Krakatoa: The first modern tsunami
By Simon Winchester
Expert on the Krakatoa eruption

It is not the first time that a major seismic event in Indonesia has made front-page news around the world. In the 1880s, close to the epicentre of this Boxing Day´s earthquake, huge waves crashed into countries all around the Indian Ocean. It was the eruption of the volcano Krakatoa.

A German, the manager of a quarry, wrote his recollections of being swept away.

He was carried off the top of his three-storey office building at the summit of a 30m high hill.

The tsunami that roared in from the sea that Monday morning in 1883 must have been 40m high, at least.

He recalled being carried along on the wave´s green unbroken crest, watching the jungle racing below, paralysed with fear.

Then suddenly to his right, he saw, being swept along beside him, an enormous crocodile.

With incredible presence-of-mind he decided the only way to save himself was to leap aboard the crocodile and try to ride to safety on its back.

How he did it is anyone´s guess, but he insists he leapt on, dug his thumbs into the creature´s eye-sockets to keep himself stable, and surfed on it for 3km

He held on until the wave broke on a distant hill, depositing him and a presumably very irritated croc on the jungle floor.

He ran, survived, and wrote about the story.

First modern catastrophe

It is an account now formally recorded in the archives as part of the official report of the first catastrophe of the modern age, the eruption of Krakatoa in August, 1883.

The same geological suture line that caused the recent Sumatran earthquake was responsible for Krakatoa, and the effects, tragic and disastrous, were uncannily similar and world-affecting.

First came an ear-splitting bang.

It was the loudest sound ever made since mankind started noting such things.

The police chief over on Rodriguez Island heard it clearly, like a cannonade of naval gunfire, but he was 4,776km away.

It was like people in London hearing, with perfect clarity, an explosion in Baltimore, or Khartoum.

Then the island exploded with a cataclysmic eruption, hurling a tower of ash, cloud and fire nearly 48km high, and raining down enormous islands of pumice, which were later found floating, laden with skeletons, 6,500km away.

And then there were the waves, four of them.

Immensely tall, immensely fast, felt as far away as France and England.

They smashed into the shores on Java and Sumatra, laying waste to everything, killing nearly 40,000 people.

Aftermath

Wreckage lay uncleared for years.

An iron naval patrol boat was carried nearly three miles inland, and stayed there for more than a century.

I found bits of it, rusted and covered with creepers, back in the 1990s.

Physically, the East Indian islands recovered, as mankind always does.

After all, the biggest volcanoes in human history, Toba and Tambora, exploded nearby, but their only legacy is myth, and their miseries are long forgotten.

But psychologically and physically the effects of Krakatoa were profound, as the intangible consequences of truly immense tragedies often are.

The defining difference about Krakatoa was that the news of it spread around the world in minutes, because the undersea telegraph cables had just been laid.

It was, if you like, the first event of today´s global village.

Looking for answers

But though the world had the information about the event, it still lacked explanation and understanding for what had happened.

Science would not come with answers as to why earthquakes and volcanoes really happened until the 1960s.

And so the world was frightened and bewildered.

Its people turned to God for answers.

Nowhere more so than in Java itself, where the local Islamic priests insisted that the eruption was a sign of Allah´s displeasure, and organised rebellions against the Dutch rulers of the time.

What strikes me as most odd about the aftermath of such events, though, is that not only do people recover, but they invariably go back.

Magnetically tempting!

The most geologically risky places to live are invariably the most attractive.

Mountain chains, coastlines, peninsulas, islands, set down as they are for some dramatic geological reason, are all too often magnetically tempting to mankind.

People live in their millions near San Francisco, a place of terrible danger.

Elsewhere in America, the Oregon coast is long overdue for a tsunami and Yellowstone will surely soon explode.

Japan is a seismic nightmare.

The Philippine volcanoes erupt and villages are built right over the fertile lava fields, right in the path of the next catastrophe.

And thousands now live along the coasts overlooking the beautiful relics of Krakatoa island, ominously still smoking each day.

Soon, no doubt, villages will spring up once more in Banda Aceh and south of Trincomalee, in Sri Lanka, and along the coasts of Tamil Nadu.

Man seems to prefer to live on the edge, and to shy away from where it is safe, from places like Nebraska, or the great plains of Siberia.

Man decides where to live, the earth decides whether to allow it.

Or, as the adage has it: Man exists on this earth subject to geological consent, which can be withdrawn at any time.

From Our Own Correspondent was broadcast on Saturday, 8 January 2005 at 1130 GMT on BBC Radio 4.

Story from BBC NEWS:
[link to news.bbc.co.uk]

Published: 2005/01/08 12link to www.godlikeproductions.com] alt=':11:'>13 GMT



Early warning technology - is it enough?
By Julianna Kettlewell
BBC News science reporter


The Pacific system works in quite a simple way
There is a sense of helplessness and soul-searching after the tsunami last week that killed more than 140,000 people.

Naturally, nations have turned their attention to exploring how such massive loss of life might be prevented in future.

A summit has now decided to create a tsunami early warning system for the Indian Ocean. The high-tech equipment could detect tsunamis that are still miles out at sea.


See how the warning system works
If disaster strikes twice, it could buy time - enough time, perhaps, to save hundreds of thousands of lives.

But unless you can warn people in remote areas, the technology is useless.

"There´s no point in spending all the money on a fancy monitoring and a fancy analysis system unless we can make sure the infrastructure for the broadcast system is there," said Phil McFadden, chief scientist at Geoscience Australia, which has been tasked with designing an Indian Ocean system by the Australian government.

"That´s going to require a lot of work. If it´s a tsunami, you´ve got to get it down to the last Joe on the beach. This is the stuff that is really very hard."

Emergency response

The Pacific basin already has a warning system and, when there was a rash of tsunamis in the 60s, it proved invaluable.

"Although I couldn´t put a number on it, a lot of lives have been saved by the Pacific early warning system," Paul Whitmore, of the West Coast and Alaska Tsunami Warning Centre, told the BBC News website.

The Pacific system, which cost tens of millions of dollars to install, works in quite a simple way. A pressure sensor sits on the bottom of the ocean and measures the weight of water above it.

If a tsunami passes overhead the pressure increases and the sensor sends a signal to a buoy sitting on the sea surface.

The buoy then sends a signal to a satellite, which in turn alerts a manned early warning centre.

But, as Dr Whitmore put it: "The warning system is more than just a warning centre. You have to have communication from the centre and then you need some sort of emergency response infrastructure.

"And that is really the hardest part, getting a localised emergency response."

An operator sitting in an early warning centre in Jakarta might know about an impending tsunami, but how does he warn the fisherman in Sumatra, the sweet seller in Sri Lanka, the tribesman on Nicobar island?

In many of these places TV, radio, even a telephone, is not an option.

Therefore, many experts say the biggest challenge is to establish an effective infrastructure, which can reach everybody - no matter how remote.

"The population must be educated about tsunamis and how to respond when it comes," said Professor Bill McGuire, director of the Benfield Hazard Research Centre at University College London.

"It is also critical that the final chain in the communication cascade - from emergency managers to population - is efficient and effective."

Communication failure

Tragically, it seems it was the final chain in the communication cascade that failed on Boxing Day. The truth is people did know about the earthquake, they did know about the tsunami threat, they just didn´t know how to tell people.


The warning system could save lives, say some experts
The Pacific Tsunami Warning Centre in Hawaii picked up the earthquake. But despite the phone calls they made, the emergency response in Asia did not exist.

Powerful computers in a Vienna office building also picked up the seismic activity. Computers at the Comprehensive Nuclear Test-Ban Treaty (CTBT) Organisation are designed to monitor nuclear explosions anywhere in the world but, as a side-effect, they also detect earthquake vibrations.

Although the organisation´s staff were on holiday, the information was automatically sent to several countries including Indonesia and Thailand but, again, the emergency infrastructure was missing.

Nearly everyone agrees an early warning system is needed in the Indian Ocean. Indeed, existing technology - like that used at the CTBT organisation - could play a vital role.

But the hard part will be developing a way of informing every swimmer and every fisherman.

Professor McGuire says that although the response infrastructure does need to be organised, it doesn´t need to be complex.

"I think sirens could play an important role," he told BBC News website. "Also, in Bangladesh they have dramatically reduced casualties in cyclones by using officials on bicycles blowing whistles to get people to the cyclone shelters.

"The solution need not be high-tech."

PACIFIC TSUNAMI WARNING SYSTEM

1. Seismic observatories in the region detect an earthquake and send data to the Pacific Tsunami Warning Center in Hawaii.
2. If the earthquake is in the Pacific basin and above 7.5 on Richter scale, an initial "Tsunami watch" alert is sent out.
3. Data from monitoring stations deep on the seabed near the the earthquake´s epicentre is checked for signs of a tsunami.
4. If a tsunami is detected, full warnings are sent out via national systems which have been set up in several countries.