Hidden fault amplified 2004 Indian Ocean tsunamiDecember 25th, 2009 - 2:39 pm ICT by ANI
Washington, December 25 (ANI): In a new research, scientists have found that the devastating 2004 Indian Ocean tsunami was amplified by a hidden fault.
Scientists thought the culprit behind the deadly waves was the magnitude 9.2 Sumatra-Andaman earthquake, one of the most powerful ever seen.
According to a report in Discovery News, it turns out the quake had help from a fault few scientists even knew existed.
Several new studies indicate that the much smaller fracture spawned a separate tremor that sent a 100-foot-high wall of water barreling into Indonesia’s Aceh province.
If true, the discovery would shed light on what really spawned the 2004 disaster.
The main earthquake broke along a 1,600-kilometer-long section of fault where the India tectonic plate grinds underneath the Sunda plate.
The fault is thought to have slipped 20 to 25 meters (65.6 to 82 feet) almost instantaneously.
Felix Waldhauser of Columbia University and a team of researchers analyzed thousands of aftershocks in the area since 2004.
Epicenters from the small quakes lined up with this unusual fault, suggesting that it, and not the main fault, has been active in this area since the disaster.
Crucially, this fault, which the team calls a “splay” fault, slices through the Sunda plate much closer to Sumatra’s west coast, and at a much steeper angle to the ocean floor than the main fault.
This means that whenever this splay fault breaks, it pushes the ocean floor upward more forcefully, causing a larger tsunami.
“Observations of the earthquake along the (main fault) were not enough to generate a tsunami that big,” Waldhauser said.
Another team of researchers led by Satish Singh of the Institut de Physique du Globe de Paris in France showed in computer models that the splay fault only had to slip 5 meters (16.4 feet) in order to generate the massive tsunami that engulfed Banda Aceh - the equivalent of a magnitude 7.8 or 7.9 earthquake.
Disturbingly, this massive event was lost amid the chaos of events on December 26, 2004.
Though the smaller quake had only 2 percent the energy of the Sumatra-Andaman rupture, it focused its wrath on Banda Aceh in the form of 100-foot-high surge of water.
“Our worry is that such a small event can produce such a devastating effect, and it will not get noticed,” Singh said. (ANI)
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