Asian earthquake and tsunami moved islands, shortened days<\/p>\n
Jim Loney, Reuters\/Jakarta<\/p>\n
The massive earthquake that triggered the Asian tsunami wobbled
\nthe earth on its axis, forced cartographers back to the drawing
\nboard and changed time by a fraction, but there's no need to
\nadjust your clocks.<\/p>\n
Six weeks after the tsunami that may have killed 300,000
\npeople on the shores of the Indian Ocean, scientists are
\ndiscovering more about the changes wrought by the magnitude-9
\nquake, the fourth-largest in the last century.<\/p>\n
It caused upheaval on the sea floor near its epicenter off the
\nnorthwest coast of Indonesia's Sumatra island and moved several
\nother islands, but scientists say any movement of land mass can
\nbe measured in inches rather than tens of yards.<\/p>\n
Chen Ji, a seismologist at the California Institute of
\nTechnology, said he found movement along the fault line of about
\n33 feet laterally and 13-16 feet vertically.<\/p>\n
But reports that the entire island of Sumatra -- 1,060 miles
\nlong and 250 miles wide -- moved 115 feet or more are wildly
\ninaccurate, scientists say.<\/p>\n
"We know we have movements of over a meter, perhaps a couple
\nof meters," said Ken Hudnut, a California-based geophysicist with
\nthe U.S. Geological Survey. "But the idea that Sumatra has moved
\n100 feet is just wrong."<\/p>\n
Scientists are working on precise measurements by comparing
\ngeographic points whose locations were known before the quake
\nwith their new positions using the Global Positioning System,
\nwhich reads exact locations by satellite.<\/p>\n
High-tech British and U.S. ships are investigating changes to
\nthe sea bed and local authorities are measuring depths in
\ncritical shipping channels.<\/p>\n
Shorter day
\nScientists at NASA, the U.S. space agency, said the Dec. 26 quake
\n-- the largest to rattle Earth since 1964 in Alaska -- disrupted
\nthe planet's rotation and shaved 2.68 microseconds, or millionths
\nof a second, from the length of a day.<\/p>\n
NASA scientists B. F. Chao and Richard Gross calculated it
\nshifted Earth's mean north pole about 1 inch and made the planet
\nslightly less oblate, or flattened at the poles.<\/p>\n
Physically, this is analogous to a spinning skater drawing
\narms closer to the body, resulting in a faster spin," they wrote
\nin an article in Eos, a publication of the American Geophysical
\nUnion.<\/p>\n
But they said these changes are based on calculations rather
\nthan measurements. The changes are so small they are either
\ndifficult to measure or too small to detect.<\/p>\n
Many earthquakes shake the planet's axis and affect its
\nrotation, scientists added, but their impact is too small to
\nmeasure.<\/p>\n
But environmental damage from the tsunami was vast. The killer
\nwaves gouged beaches, crushed coral reefs, smashed thousands of
\nacres of mangrove forests and refashioned coastlines from
\nThailand to Somalia.<\/p>\n
A preliminary survey by Indonesia's government and the United
\nNations Environmental Program (UNEP) estimated the economic cost
\nto the environment at $675 million in Indonesia alone.<\/p>\n
The survey said 60,000 acres of mangroves and 70,000 acres of
\ncoral reefs were damaged.<\/p>\n
Reefs, mangroves<\/p>\n
Some coral reefs -- undersea gardens that act as shelter and
\nnursery to a wide range of marine species -- were crushed by the
\nwaves. Corals grow slowly, some only an inch or two a year, so
\ntheir recovery could take decades.<\/p>\n
John Pernetta, a UNEP official in Bangkok, said the extent of
\ndamage to some of the coral reefs around Thailand was very high
\n-- up to 80 percent in some places. Their recovery was uncertain.<\/p>\n
Mangroves torn out by the waves will fare better, he said, as
\nthey leave behind roots and seeds that will help them regenerate.<\/p>\n
"Long-term damage to mangroves by hurricanes or tsunamis
\ndoesn't really happen," Pernetta said. "After five to 10 years
\nyou don't even know anything has happened."<\/p>\n
Vast stretches of Sumatra's west coast were turned brown by
\nthe tsunami as rice paddies and other vegetation were swamped by
\nsalt water. It could take two or three rainy seasons to wash the
\nsalt from the saturated land, experts say.<\/p>\n
The tsunami waves ate away beaches and coastal areas in
\nThailand, Indonesia and Sri Lanka, radically changing maps.
\nThe waves also carried sediment ashore, said Phil Liu, a Cornell
\nUniversity wave researcher who led a scientific team to Sri Lanka
\nin mid-January.<\/p>\n
"There is evidence that a lot of sediment was being brought
\nonshore," he said. "A post office on the east coast was found
\nwith sediment deposits on the roof."<\/p>\n
But it remains to be seen whether such sediment is good for
\nthe land or a bane because of its high salt content.<\/p>",
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