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tsunamis travel fast but not at infinite speed

this article is now much expanded and updated at this
illustrated briefing document

This is probably the main source tracking the Sumatra tsunami. Animation of the first few hours only, so far. Bangladesh appears to have escaped lightly, despite having 17 million people living less than one metre above sea level. Another animation of the first three hours. These show weaker waves going North and South, than the waves going East and West. This is probably why much of India and Bangladesh has been little affected.

There is a good write-up from the overseers of the US Tsunami Service, NOAA and Tsunamis.

“The waves radiate outward in all directions from the disturbance and can propagate across entire ocean basins. For example, in 1960 an earthquake in Chile caused a tsunami that swept across the Pacific to Japan. Tsunami waves are distinguished from ordinary ocean waves by their great length between peaks, often exceeding 100 miles in the deep ocean, and by the long amount of time between these peaks, ranging from five minutes to an hour. The speed at which tsunamis travel depends on the ocean depth. A tsunami can exceed 500 mph in the deep ocean but slows to 20 or 30 mph in the shallow water near land. In less than 24 hours, a tsunami can cross the entire Pacific Ocean.

“In the deep ocean, a tsunami is barely noticeable and will only cause a small and slow rising and falling of the sea surface as it passes. Only as it approaches land does a tsunami become a hazard. As the tsunami approaches land and shallow water, the waves slow down and become compressed, causing them to grow in height. In the best of cases, the tsunami comes onshore like a quickly rising tide and causes a gentle flooding of low-lying coastal areas.”

update 2

From Earthquake Central, tectonic maps and many links.

Earthquake statistics.

Indian Ocean tectonic plates.

Details for Sumatra area, Richter 9.

Preliminary Earthquake Report, with tectonic plate map (over large region)

“"From the size of the earthquake, it is likely that the average displacement on the fault plane was about fifteen meters. The sea floor overlying the thrust fault would have been uplifted by several meters as a result of the earthquake.”

• Islands are being reported as moved laterally in the area by several metres have probably not moved sideways, but been upthrusted thus changing their coast lines.
  
  
• large quakes from the past century:

  “[...] the magnitude 9.5 1960 Chile earthquake, the magnitude 9.2 1964 Prince William Sound, Alaska, earthquake, the magnitude 9.1 1957 Andreanof Islands, Alaska, earthquake, and the magnitude 9.0 1952 Kamchatka earthquake.”

update 3

• “Many who escaped death in what was possibly the deadliest tsunami in more than 200 years now face hunger and disease. The United Nations mobilized what it called the biggest relief operation in its history [...] ”
  
  “A tsunami in 1883 at Krakatoa, off southern Sumatra, killed 36,000 and one in the South China Sea in 1782 killed 40,000, according to the U.S. National Geophysical Data Center.” [Quoted from Reuters]

Mt Fuji seen from the sea, Hokusai, woodcut, 1834

• “The deadly Asian earthquake may have permanently accelerated the Earth's rotation -- shortening days by a fraction of a second -- and caused the planet to wobble on its axis [...] ” [Quoted from tvnz.co.nz]
  
  
• Present estimates suggest that this earthquake had the energy of more than 10,000 Hiroshima bombs, that is between 150 to 200 million tons of TNT
  
  
• The last large tectonic event also this fault resulting in an earthquake was in 1843. Thus the pressures and forces have had over a century to build up. This is why the sea-quake was so powerful (9.0 on the Richter scale).
  
  
• The largest tsunami recorded measured 210 feet, about 18 stories above sea level, when it reached Siberia's Kamchatka Peninsula in 1737 - probably!
  [33 feet has been reported so far for the Sumatran tsunami.]

A tsunami animation of the Pacific region [2.4mb .mov file].

“LOS ANGELES: US officials who detected a massive earthquake off Asia's coast tried frantically to warn the deadly wall of water was coming, the head of the Pacific Tsunami Warning Centre has said.

“But there was no official alert system in the region because such catastrophes only happen there about once every 700 years, said Charles McCreery, director of the National Oceanic and Atmospheric Administration's Centre in Honolulu.

“ "We tried to do what we could," McCreery said. "We don't have contacts in our address book for anybody in that part of the world."

“Within moments of detecting the quake, McCreery and his staff were on the phone to Australia, then to US Naval officials, various US embassies and finally the US State Department.”

“ US officials are now trying to help officials in the region set up some sort of informal warning system and feeling badly that more couldn't have been done, McCreery said.

“ "It took an hour and a half for the wave to get from the earthquake to Sri Lanka and an hour for it to get...to the west coast of Thailand and Malaysia," he said. "You can walk inland for 15 minutes to get to a safe area." ” [Quoted from stuff.co.nz]

Reports [30.12.04] are now giving estimates of well over 100,000 dead - approximately 1/60,000 of the world population, or the population of a UK town like Oxford (135,000); and millions washed out.

Seismic map [link from the auroran sunset, where there is more detailed reporting.]

update 4 - further links and information, completed at illustrated briefing document on tsunamis

Causes of tsunamis:

• earthquakes,
• landslips or landslides,
• asteroids.

The behaviour of a tsunami wave when caused by subduction [as happened with Sumatra]. With diagrams.

A NASA subduction diagram

“Description: The majority of earthquakes and volcanoes around the world occur at the intersection of plate boundaries. This diagram shows the subduction of an ocean plate underneath a continental plate. Earthquakes are caused by the two plates moving relative to each other, and volcanoes are formed when ocean crust, forced under the lighter continental crust, melts and then rises to the Earth's surface. The Andes have been forming over the past 170 million years as the Nazca Plate lying under the Pacific Ocean has forced its way under the South American Plate and pushed up its western edge. The subduction of one plate under the other has given rise to a number of volcanoes that dot the western edge of the mountain range.”

Diagram showing overthrust and subduction areas in Sumatra region.

A very long item on the risk of landslide/landslip-generated tsunamis. The Canary Islands and Hawaii are discussed in detail.

“The most damaging tsunami on record before 2004 was the one that killed an estimated 40,000 people in 1782 following an earthquake in the South China Sea. In 1883 some 36,500 people were killed by tsunamis in the South Java Sea, following the eruption of Indonesia's Krakatoa volcano. In northern Chile more than 25,000 people were killed by a tsunami in 1868.

“The Pacific is by far the most active tsunami zone, according to the U.S. National Oceanic and Atmospheric Administration (NOAA). But tsunamis have been generated in other bodies of water, including the Caribbean and Mediterranean Seas, and the Indian and Atlantic Oceans. North Atlantic tsunamis included the tsunami associated with the 1775 Lisbon earthquake that killed as many as 60,000 people in Portugal, Spain, and North Africa. This quake caused a tsunami as high as 23 feet (7 meters) in the Caribbean.”
[Quoted from National Geographic.com]

this article is now much expanded and updated at this
illustrated briefing document

the web address for the article above is
https://www.abelard.org/news/science0412.php#tsunami

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electric armour

“Dstl scientists have recently demonstrated an armoured troop carrier protected by Electric Armour, in which, when danger threatens, an outer skin of metal plates can rapidly be electrified to several thousand volts. When hit by a RPG or other shaped charge warhead, the incoming copper jet has to pass through the electrified layers, where it has to endure the passage of many thousands of amperes of current.

“As is well known, a current of just thirteen amps is sufficient to 'blow' and disintegrate the fuse of a household electrical appliance. Similarly, the high speed copper jet from a shaped charge anti-tank warhead is virtually instantaneously dispersed by the high temperatures and powerful fields generated by the so-called 'Pulsed Power' System carried by the vehicle. Any residual debris is absorbed by the vehicle's ordinary armoured hull.”

Does it work with other than copper?
How long can it be run?

lead from Limbic

end note

“Rocket Propelled Grenades (RPGs) [...] upon impact its 'shaped charge' explosive warhead shoots a rapier-like jet of hot copper into the target at several miles per second. Such jets can penetrate anything upwards of a foot (30cm) of solid steel armour.”

the web address for the article above is
https://www.abelard.org/news/science0412.php#electric_armour

martian rover car-wash

“Exciting and unexplained events” are cleaning the Mars rover Opportunity so that its solar panel output is still at over 900 watt-hours a day, unlike its companion rover, Spirit. Spirit’s output has dropped to 400 watt-hours/day, in part because of dust-caked solar panels. The two NASA rovers started their Mars explorations with a solar-panel energy output of over 900 watt-hours a day.

“Whatever the process, it has taken place while Opportunity was parked during the Martian night. On at least four occasions over a six-month period, the rover's power output increased by up to 5% overnight.”

In trying to understand this mystery, NASA Mars scientists have even had Opportunity photographically inspect itself to see why it is running so well. The reason is.....

Opportunity’s solar panels have been cleaned!

But who is/are the kindly helper/s to Opportunity? The good fairy? The little green men?

“The answer might lie in the nature of the two rovers' missions. Spirit has been prospecting in an area called Columbia Hills, while Opportunity has been exploring the wall of Endurance crater.

“While climbing, Opportunity spent a lot of time with its solar panels tilted, which could have caused any dust to tumble off. And the researchers suspect the shape of the crater may encourage the development of dust devils or other wind patterns that could help scrub the panels.

“If the crater does provide a natural, wind-driven car wash then Opportunity's days as a clean machine could be at an end. On 12 December, it drove out of the crater to explore the terrain beyond. "If in three or four months Opportunity is still operating and hasn't had another power boost that would suggest the crater was the key," [...] ” [Quoted from newscientist.com]

Well, if it’s the crater, the thing to do is to regularly send the rover Opportunity back to the Endurance crater for a “car-wash”.

the web address for the article above is
https://www.abelard.org/news/science0412.php#rover_wash

the geminids are coming!

“ "You can begin to see the Geminids almost as soon as it gets dark," Cooke said. "You won't see many but you'll see them and you can see them all night." ”

Note that these comments are Eastern USA-based, where the peak showers will be soon after midnight. They are expected to reach about one a minute around this time (The best times will be 04.00 to 05.00 in western Europe.) There will be some Geminids visible at other times. Observers in other regions will have different observation time-windows.

“The source of the shower is asteroid 3200 Phaethon. There's a cloud of dust trailing the asteroid and Earth plows through it every year in mid-December.” [Quoted from yubanet.com, includes sky chart]

“Many Geminids appear yellowish in hue. Some even seem to form jagged or divided paths.

“According to meteor specialist Neil Bone, at 2 grams per cubic centimeter on average, Geminid meteoroids are several times denser than the cometary dust flakes that supply most meteor showers, so they burn up less quickly. Add this to the relatively slow speed with which Geminids typically encounter Earth – 22 miles per second (35 kilometers per second), or roughly half the speed of a Leonid meteor – and you have the recipe for meteors that linger a bit longer in view than most.
—
“In other parts of the world, such as Europe, Asia and Australia, the Geminid peak will come during local daylight hours.

“The Geminids are named for the constellation of Gemini, the Twins. On Dec. 13-14, the night of this shower’s maximum activity, the meteors appear to emanate from a spot in the sky near the bright star Castor in Gemini as Earth barrels through a stream of space debris laid down centuries ago.” [Quoted from spacewatch , includes link to sky chart]

related material
Universal Time (UT) and time zone calculators

the web address for the article above is
https://www.abelard.org/news/science0412.php#geminids

radio-active contraband smuggling

Incidents concerning fissile material seem to be dropping, while those with less dangerous material increases.

The development: a detector in a phone aimed at use by police, customs etc.

“The challenge for the LLNL engineers was to devise a radiation sensor cheap enough to make the project viable. "It’s relatively straightforward to make a $10,000 radiation detection device that works well," says project leader Bill Craig at LLNL’s Radiation Detection Center. "But the target price of these units is $1000. That’s the phone, the whole thing." ”

the web address for the article above is
https://www.abelard.org/news/science0412.php#radioactive

running on water
studying locomotion.

“[...] the lack of answers to such questions is holding up the development of new technologies. It's one of the major reasons we can't build effective legged robots, [...] ”
—
“[...] Throughout their size range, they can run across water on their hind limbs at about 5 feet (1.5 meters) a second for a distance of approximately 15 feet (4.5 meters) before they sink to all fours and swim. The lizard is often called the Jesus Christ lizard in Central America [...]”
—
“ The stride is divided into three phases: the slap, the stroke, and the recovery. During the slap the foot moves primarily vertically downward. During the stroke it moves primarily backward. And during the recovery the foot moves up and out of the water, returning to the start position of the next step.”
—
“ According to analysis of their video, the lizards generate force for support during the slap phase, in which the lizards' foot plunges straight down, pushing water down and away from the foot while creating a pocket of air surrounding the foot.

“The support force generated by the slap is sufficient to keep the lizards' bodies above the water's surface during the stroke phase in which they propel themselves forward by kicking their leg back through the water.”

Article has more details, including a side bar on how insects (water-skaters) do it.

the web address for the article above is
https://www.abelard.org/news/science0411.php#jesuschrist_lizard

update 2 scramjet test successful - new speed record

Preliminary data from the scramjet-powered research vehicle show its revolutionary engine worked successfully at approximately Mach 10, nearly 7000 mph, as it flew at an altitude of approximately 110,000 feet.

More details on the NASA site, including movies.

NASA scramjet breaks sky speed record - update: flight delayed 'til tomorrow

Image credit: NASA Dryden Flight Research Center Photo Collection
NASA photo: EDO4-0082-4

CTV News: John Vennavally-Rao on the X-43A
[web-tv report showing previous test flight]

NASA scientists have achieved a technological breakthrough with their successful test of an experimental high-speed jet, the X-43A.

In its 11-second flight, the aircraft reached speeds of 8,000 kilometres per hour.

What is a scramjet?

A conventional rocket carries its own oxygen supply,
A conventional jet engine draws in air and burns it with fuel so it expands in a combustion chamber.
A ramjet scoops oxygen directly from the atmosphere, while travelling at subsonic speeds.
A scramjet scoops oxygen directly from the atmosphere.
Scramjets operate at supersonic speeds.

A scramjet burns fuel in a stream of supersonic air compressed by the forward speed of the aircraft. In each case, the hot air is then forced out the exhaust nozzle to produce thrust.

related material
“the first time an air-breathing scramjet-powered aircraft has flown freely”

the web address for the article above is
https://www.abelard.org/news/science0411.php#scramjet_record

robot maintenance will prolong life of hubble telescope

Yet largely because of the Canadian robot named "Dextre," NASA has gone in less than a year from virtually writing off the Hubble to embracing a mission that will cost between $1 billion and $1.6 billion and approach in complexity the hardest jobs the agency has ever undertaken.
—
To do it, the United States must develop its first-ever robotic docking vehicle, fill a bag with tools that, in many cases, have not been invented, and use the robot repairman to unscrew j-hooks, open and shut doors and "drawers," disconnect and attach electric connectors, and rig jumper cables.
—
In the past, shuttle astronauts had the job of servicing Hubble, missions that required a few days of spacewalks lasting six hours each. Dextre "can work 24-7," Weiler said -- a fortunate feature, because robots are not as supple as humans. "Watching it is like watching grass grow," Weiler said.

the web address for the article above is
https://www.abelard.org/news/science0411.php#hubble_robot

update: ion-propelled craft now in moon orbit

The craft arrived at its destination thirteen months after launching from Earth. Although the moon is only 380,000km away in a straight line, SMART-1 orbited the Earth more than 300 times, and travelled 84m km. In fact, its journey comparable in length to an interplanetary cruise: at its closest, Venus is just 40m km away from us, and Mars is 35m km.

SMART-1 slotted into orbit at an altitude of 5000km, and will settle into its final orbit over the next few months. Its ion-propulsion engine will fire continuously for the next four days to help it stabilise. By January, it should be in an elliptical orbit, passing the moon at a distance of 300km over the South pole, and 3000km over the North pole.

ion-propelled craft gently nears the moon

“Conventional spacecraft engines rely on chemical reactions to generate gas, which pushes the craft forwards as it squeezes out of the engine, in the same way as a deflating party balloon will fly across a room. But in space, mass is money. Whereas chemical engines must carry two fuel substances to react together (often hydrogen and oxygen), SMART-1's ion drive carries only xenon, making it lighter and cheaper.

“The success of SMART-1, which stands for Small Missions for Advanced Research in Technology, in reaching the Moon has proved that future spacecraft could use the same engines to get to Mercury and Mars, [...] ”

related material
ion engine under test in space

the web address for the article above is
https://www.abelard.org/news/science0411.php#ion_propulsion

email email_abelard [at] abelard.org

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the address for this document is https://www.abelard.org/news/science0412.php

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