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NASA Details Earthquake Effects on the Earth.

NASA scientists using data from the Indonesian earthquake calculated it affected Earth's rotation, decreased the length of day, slightly changed the planet's shape, and shifted the North Pole by centimeters. The earthquake that created the huge tsunami also changed the Earth's rotation.Dr. Benjamin Fong Chao, of NASA's Goddard Space Flight Center, Greenbelt, Md. and Dr. Richard Gross of NASA's Jet Propulsion Laboratory, Pasadena, Calif. said all earthquakes have some affect on Earth's rotation. It's just they are usually barely noticeable. "Any worldly event that involves the movement of mass affects the Earth's rotation, from seasonal weather down to driving a car," Chao said. Chao and Gross have been routinely calculating earthquakes' effects in changing the Earth's rotation in both length-of-day as well as changes in Earth's gravitational field. They also study changes in polar motion that is shifting the North Pole. The "mean North pole" was shifted by about 2.5 centimeters (1 inch) in the direction of 145º East Longitude. This shift east is continuing a long-term seismic trend identified in previous studies.They also found the earthquake decreased the length of day by 2.68 microseconds. Physically this is like a spinning skater drawing arms closer to the body resulting in a faster spin. The quake also affected the Earth's shape. They found Earth's ob lateness (flattening on the top and bulging at the equator) decreased by a small amount. It decreased about one part in 10 billion, continuing the trend of earthquakes making Earth less oblate. To make a comparison about the mass that was shifted as a result of the earthquake, and how it affected the Earth, Chao compares it to the great Three-Gorge reservoir of China. If filled the gorge would hold 40 cubic kilometers (10 trillion gallons) of water. That shift of mass would increase the length of day by only 0.06 microseconds and make the Earth only very slightly more round in the middle and flat on the top. It would shift the pole position by about two centimeters (0.8 inch).The researchers concluded the Sumatra earthquake caused a length of day (LOD) change too small to detect, but it can be calculated. It also caused an oblateness change barely detectable, and a pole shift large enough to be possibly identified. They hope to detect the LOD signal and pole shift when Earth rotation data from ground based and space-borne position sensors are reviewed.The researchers used data from the Harvard University Centroid Moment Tensor database that catalogs large earthquakes. The data is calculated in a set of formulas, and the results are reported and updated on a NASA Web site. The massive earthquake off the west coast of Indonesia on December 26, 2004, registered a magnitude of nine on the new "moment" scale (modified Richter scale) that indicates the size of earthquakes. It was the fourth largest earthquake in one hundred years and largest since the 1964 Prince William Sound, Alaska earthquake.The devastating mega thrust earthquake occurred as a result of the India and Burma plates coming together. It was caused by the release of stresses that developed as the India plate slid beneath the overriding Burma plate. The fault dislocation, or earthquake, consisted of a downward sliding of one plate relative to the overlying plate. The net effect was a slightly more compact Earth. The India plate began its descent into the mantle at the Sunda trench that lies west of the earthquake's epicenter.
Nasa details Moon and Mars plan.
The US space agency Nasa has announced detailed plans for sending humans back to the Moon and eventually onwards to Mars.
Nasa wants to send a crew of four to the Moon in 2018 for a one-week stay.
The Crew Exploration Vehicle, the spacecraft that will take them there, should be ready by 2012, officials say.
Astronauts on the 2018 mission might return to the Moon in a capsule similar to those used in the Apollo programme but using space shuttle technology.
Humans have not set foot on the Moon since the Apollo 17 mission in 1972
Nasa is charged with implementing the vision for space exploration, laid out in January 2004 by President George W Bush.
This vision aims to return humans to the Moon, to use it as a staging point for a manned mission to Mars.
Expensive plans
The American space agency briefed congressional committees on Friday on its plans to spend a reported $100bn developing the spacecraft and associated technology for the lunar programme.
Research aboard the International Space Station is also expected to be cut.
The space shuttle is to be retired by 2010 in order to pay for its replacement, known as the Crew Exploration Vehicle (CEV).
Nasa would begin the lunar expedition by lifting a lunar landing capsule and a propulsion stage into space.
It would then launch the CEV atop a new launcher using existing shuttle rocket technology.
The CEV would dock with the lunar lander and the propulsion stage and start its journey to the Moon.
Nasa also envisions the possibility of building a semi-permanent lunar base, where astronauts would make use of the Moon's natural resources for water and fuel.
Even before the official announcement, there has been recognition that the proposals will be tough to see through, given the US government's commitments to the Iraq war and recovery from Hurricane Katrina.
"This plan is coming out at a time when the nation is facing significant budgetary challenges," Representative Bart Gordon, a Tennessee Democrat on the US House Science Committee, said in a statement.
"Getting agreement to move forward on it is going to be heavy lifting in the current environment, and it's clear that strong presidential leadership will be needed."