"I'm this great picture of the Army."
I am sorry. I didn't send you nor did I ever want to send you.
Tuesday, December 28, 2004
Earthquake Spawns Tsunamis
The Earth’s solid surface floats on a layer of softer rock as a collection of interlocking, movable puzzle pieces called tectonic plates. At 7:58 a.m. (local time), on December 26, 2004, beneath the Indian Ocean west of Sumatra, Indonesia, pent-up energy from the compressional forces of one tectonic plate grinding under another found a weak spot in the overlying rock. The rock was thrust upward, and the Earth shook as a 9.0 magnitude earthquake sent its vibrations out into the ocean. Tsunamis spread out in all directions; the massive waves washed over islands and crashed against coastlines in Sri Lanka, Southern India, and even the east coast of Africa. Tens of thousands of people were killed; millions are homeless.
The image above shows how the tectonic puzzle pieces fit together around Indonesia. The epicenter of the recent quake is marked with a red star in the image. It is located just to the east of the Sunda Trench, where the India Plate begins to get subducted beneath (forced under) the Burma Plate. The blue arrows along the plate boundary show the direction of subduction.
As the India Plate slides beneath the Burma Plate, it meets pockets of resistance, which causes compressional forces to build up. Weakened overlying rock gets forced upward. Based on the location of aftershocks (red shaded circles on the image), the United States Geological Survey reports that approximately 1,200 kilometers of the plate boundary probably slipped as a result of the quake. The initial rupture was likely more than 100 kilometers wide, and probably produced an average vertical displacement along the fault plane (the slope along which the two plates meet) of 15 meters.
When the bottom of the ocean is deformed by this type of “megathrust” quake, the upward force acts like a fist rising up from underwater. Water rolls down off the sides of the “fist,” creating massive waves that can travel as fast as an airplane. The waves can move across the ocean and barely disturb the surface, but when they reach shallow coastal water, the earthquake’s energy thrusts them tens of meters into the air. The tsunami created by this earthquake reached India and Sri Lanka in about four hours. The wave eventually reached Africa, the Pacific Ocean, Hawaii, and the west coast of North and South America.
For more information about this earthquake and plate tectonics, visit the Website of the USGS.
The image above shows how the tectonic puzzle pieces fit together around Indonesia. The epicenter of the recent quake is marked with a red star in the image. It is located just to the east of the Sunda Trench, where the India Plate begins to get subducted beneath (forced under) the Burma Plate. The blue arrows along the plate boundary show the direction of subduction.
As the India Plate slides beneath the Burma Plate, it meets pockets of resistance, which causes compressional forces to build up. Weakened overlying rock gets forced upward. Based on the location of aftershocks (red shaded circles on the image), the United States Geological Survey reports that approximately 1,200 kilometers of the plate boundary probably slipped as a result of the quake. The initial rupture was likely more than 100 kilometers wide, and probably produced an average vertical displacement along the fault plane (the slope along which the two plates meet) of 15 meters.
When the bottom of the ocean is deformed by this type of “megathrust” quake, the upward force acts like a fist rising up from underwater. Water rolls down off the sides of the “fist,” creating massive waves that can travel as fast as an airplane. The waves can move across the ocean and barely disturb the surface, but when they reach shallow coastal water, the earthquake’s energy thrusts them tens of meters into the air. The tsunami created by this earthquake reached India and Sri Lanka in about four hours. The wave eventually reached Africa, the Pacific Ocean, Hawaii, and the west coast of North and South America.
For more information about this earthquake and plate tectonics, visit the Website of the USGS.
The 'Wobble' is worse due to the diminished mass of the Polar Ice Fields and Ice Caps. The Earth is losing it's balance easily.
A Flattened Village in Indonesia
Asia Quake Gives Globe a Jolt
AFP
Dec. 28, 2004 — The gigantic Asian sea quake, the most dramatic seismic shock in more than 40 years, made the earth wobble on its axis and permanently changed the geology of the surrounding area, scientists said Tuesday.
It was like "flicking a top," said Paul Tapponnier, head of the tectonics laboratory at the Institut de Physique du Globe, France's leading center for Earth sciences.
Tapponnier said the quake deep beneath the Pacific Ocean lasted a "colossal" 200 seconds, building up huge amounts of energy in the sea that drove towering waves onto beaches throughout southern Asia.
"That earthquake has changed the map," U.S. Geological Survey expert Ken Hudnut told AFP in Los Angeles.
The quake, which had an epicenter magnitude of 9.0, struck 250 kilometers (155 miles) southeast of Sumatra.
One of the four biggest in the last century, it sent gigantic tsunami waves crashing around the Indian Ocean, causing 55,000 deaths and leaving thousands of other people missing.
Hudnut said seismic modeling suggested the quake may have moved small islands by as much as 20 meters (66 feet), and the northwestern tip of the Indonesian territory of Sumatra may also have shifted to the southwest by around 36 meters (118 feet).
"That is a lot of slip," he said.
The energy released as the two sides of the geological fault line deep beneath the sea slipped against one another would have made the Earth wobble on its axis, Hudnut said.
Tapponnier said the quake caused a 15- to 20-meter slippage of the earth's surface along a front extending for 100 kilometers (62 miles).
He said there may also have been vertical movements that possibly pushed the island of Siberut, 100 kilometers west of Sumatra, one or two meters higher, although it would be impossible to check this scientifically because of guerrilla activity in the area.
Tapponnier said it was also possible that some regions of Sumatra south of the equator have been completely swallowed up.
He said it was not rare for earthquakes to alter geological features. "Earthquakes are the architects of landscapes," he said. "All the mountains that we see today have been modeled by earthquakes."
Tapponnier said the massive 1960 earthquake off the coast of Chile shifted the local landscape by 20 meters. A quake in Alaska in 1964 pushed islands higher and sank oyster beds 12 meters (39 feet) beneath the surface.
And a 6.3 magnitude temblor off the coast of Guadeloupe last month moved the ocean floor several tens of centimeters, he added.
In Asia, "we are dealing with a quake 1,000 times more powerful" than the one off Guadaloupe, a shock powerful enough to make the earth wobble on its axis, Tapponnier said.
Hudnut agreed the earth had slightly wobbled "due to the massive amount of energy exerted and the sudden shift in mass."
But minor oscillations as the earth spins like a top are well known to astronomers. The principal causes of the slight irregular motion, known as nutation, are the Sun and Moon as they continually change location relative to one another.
Another U.S. Geological Survey geophysicist agreed that the Earth would have received a "little jog" from the quake and that the islands off Sumatra would have been shifted.
However, Stuart Sipkin, of the U.S. Geological Survey National Earthquake Information Center in Golden, Col., said it was more likely that the islands had risen higher out of the sea than they had moved laterally.
"In this case, the Indian plate dived below the Burma plate, causing uplift, so most of the motion to the islands would have been vertical, not horizontal," he said.
One type of 'Earth Wobble' is called the Chandler Wobble.
Asia Quake Gives Globe a Jolt
AFP
Dec. 28, 2004 — The gigantic Asian sea quake, the most dramatic seismic shock in more than 40 years, made the earth wobble on its axis and permanently changed the geology of the surrounding area, scientists said Tuesday.
It was like "flicking a top," said Paul Tapponnier, head of the tectonics laboratory at the Institut de Physique du Globe, France's leading center for Earth sciences.
Tapponnier said the quake deep beneath the Pacific Ocean lasted a "colossal" 200 seconds, building up huge amounts of energy in the sea that drove towering waves onto beaches throughout southern Asia.
"That earthquake has changed the map," U.S. Geological Survey expert Ken Hudnut told AFP in Los Angeles.
The quake, which had an epicenter magnitude of 9.0, struck 250 kilometers (155 miles) southeast of Sumatra.
One of the four biggest in the last century, it sent gigantic tsunami waves crashing around the Indian Ocean, causing 55,000 deaths and leaving thousands of other people missing.
Hudnut said seismic modeling suggested the quake may have moved small islands by as much as 20 meters (66 feet), and the northwestern tip of the Indonesian territory of Sumatra may also have shifted to the southwest by around 36 meters (118 feet).
"That is a lot of slip," he said.
The energy released as the two sides of the geological fault line deep beneath the sea slipped against one another would have made the Earth wobble on its axis, Hudnut said.
Tapponnier said the quake caused a 15- to 20-meter slippage of the earth's surface along a front extending for 100 kilometers (62 miles).
He said there may also have been vertical movements that possibly pushed the island of Siberut, 100 kilometers west of Sumatra, one or two meters higher, although it would be impossible to check this scientifically because of guerrilla activity in the area.
Tapponnier said it was also possible that some regions of Sumatra south of the equator have been completely swallowed up.
He said it was not rare for earthquakes to alter geological features. "Earthquakes are the architects of landscapes," he said. "All the mountains that we see today have been modeled by earthquakes."
Tapponnier said the massive 1960 earthquake off the coast of Chile shifted the local landscape by 20 meters. A quake in Alaska in 1964 pushed islands higher and sank oyster beds 12 meters (39 feet) beneath the surface.
And a 6.3 magnitude temblor off the coast of Guadeloupe last month moved the ocean floor several tens of centimeters, he added.
In Asia, "we are dealing with a quake 1,000 times more powerful" than the one off Guadaloupe, a shock powerful enough to make the earth wobble on its axis, Tapponnier said.
Hudnut agreed the earth had slightly wobbled "due to the massive amount of energy exerted and the sudden shift in mass."
But minor oscillations as the earth spins like a top are well known to astronomers. The principal causes of the slight irregular motion, known as nutation, are the Sun and Moon as they continually change location relative to one another.
Another U.S. Geological Survey geophysicist agreed that the Earth would have received a "little jog" from the quake and that the islands off Sumatra would have been shifted.
However, Stuart Sipkin, of the U.S. Geological Survey National Earthquake Information Center in Golden, Col., said it was more likely that the islands had risen higher out of the sea than they had moved laterally.
"In this case, the Indian plate dived below the Burma plate, causing uplift, so most of the motion to the islands would have been vertical, not horizontal," he said.
One type of 'Earth Wobble' is called the Chandler Wobble.
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