Advances Since the 2004 Indian Ocean Tragedy | sci-english.blogspot.com

Tsunami File photo in tamilnadu, india | sci-english.blogspot.com

The Indian Ocean tsunami was one of the worst natural disasters in history. Enormous waves struck countries in South Asia and East Africa with little to no warning, killing 243,000 people. The destruction played out on television screens around the world, fed by shaky home videos. The outpouring of aid in response to the devastation in Indonesia, Sri Lanka, Thailand and elsewhere was unprecedented.

The disaster raised awareness of tsunamis and prompted nations to pump money into research and warning systems.  on the 10th anniversary of the deadly tsunami, greatly expanded networks of seismic monitors and ocean buoys are on alert for the next killer wave in the Indian Ocean, the Pacific and the Caribbean. In fact, tsunami experts can now forecast how tsunamis will flood distant coastlines hours before the waves arrive.

But hurdles remain in saving lives for everyone under the threat of tsunamis. No amount of warning will help those who need to seek immediate shelter away from beaches, disaster experts said.


"A lot of times, you're not going to get any warning near these zones where there are large earthquakes, so we have to prepare the public to interpret the signs and survive," said Mike Angove, head of the National Oceanic and Atmospheric Administration's (NOAA) tsunami program. In 2004, the tsunami waves approached coastal Indonesia just nine minutes after the massive magnitude-9.1 earthquake stopped shaking, Angove said.


 On alert

Since 2004, geologists have uncovered evidence of several massive tsunamis in buried sand layers preserved in Sumatran caves. It turns out that the deadly waves aren't as rare in the Indian Ocean as once thought. "We had five fatal tsunamis off the coast of Sumatra prior to 2004," said Paula Dunbar, a scientist at NOAA's National Geophysical Data Center. Over the past 300 years, 69 tsunamis were seen in the Indian Ocean, she said.

Despite the risk, there was no oceanwide tsunami warning system in the region. Now, a $450 million early-alert network is fully operational, though it is plagued with equipment problems. (Even the global monitoring network loses 10 percent of its buoys each year, according to NOAA.) Essentially built from scratch, the $450 million Indian Ocean Tsunami Warning System (IOWTS) includes more than 140 seismometers, about 100 sea-level gauges and several buoys that detect tsunamis. More buoys were installed, but they have been vandalized or accidentally destroyed. The buoys and gauges help detect whether an earthquake triggered a tsunami.

The global network of Deep-Ocean Assessment and Reporting of Tsunami (DART) buoys, which detects passing tsunami waves, has also expanded, from six buoys in 2004 to 60 buoys in 2014, Angove said.

Regional tsunami alert centers have been built in Australia, India and Indonesia. Scientists at the centers decide whether a tsunami is likely based on information from the network of sensors, estimate the probable size, then alert governments to get the warning out through sirens, TV, radio and text alerts.

Getting the warnings down to people living in remote coastal areas is one of the biggest hurdles for the new system. Not all warnings reach the local level. And not every tsunami earthquake is strong enough to scare people away from shorelines. In Sumatra's Mentawai Islands, a 2010 tsunami killed more than 400 people because residents failed to evacuate in the short time between the earthquake and the tsunami's  arrival. The shaking was simply not strong enough to trigger people's fear of tsunamis, even though islanders had self-evacuated after a 2007 earthquake, according to an investigation by the University of Southern California's Tsunami Research Center. There was also no clear-cut warning from the regional tsunami alert system.

"Tsunami earthquakes remain a major challenge," Emile Okal, a seismologist at Northwestern University in Evanston, Illinois, said Dec. 15 at the American Geophysical Union's (AGU) annual meeting in San Francisco.