00:00It is 7h59 when a man, abruptly pulled out of his sleep,
00:05finds himself confronted with a mysterious and irresistible force.
00:10While he tries to understand what is happening,
00:12a gigantic column of water, 30 meters high,
00:15is already rushing towards his hometown.
00:18In less than 20 minutes,
00:19a huge devastating wave will take buildings, trees and vehicles,
00:24costing the lives of most of his loved ones and friends.
00:28This scenario can, alas, happen at any time.
00:31On December 26, 2004,
00:34thousands of tourists from Europe and America
00:37savored the pleasures of the tropical beaches of Thailand,
00:40Sri Lanka and Indonesia,
00:43when an underwater earthquake of an exceptional magnitude
00:46of 9.3 struck off the west coast of Sumatra.
00:50This earthquake, the most powerful ever recorded in Asia,
00:54triggers one of the most destructive tsunamis in history,
00:58known as the Christmas Day Tsunami.
01:01In a few hours, only 230,000 lives will be lost.
01:04The city of Bandahaset, located on the island of Sumatra in Indonesia,
01:08and populated by 260,000 inhabitants,
01:10is located closest to the epicenter.
01:12Less than 30 minutes after the earthquake,
01:14huge waves, reaching the height of a 10-story building,
01:18hit the city.
01:19More than 60,000 people die on the field,
01:22and the destruction is so catastrophic
01:24that almost no one survives in the trajectory of the waves.
01:28Then, the tsunami hit Thailand.
01:31The waves, crossing the Indian Ocean at a speed of 800 km per hour,
01:36reach the coasts of Phang Nga and Phuket
01:38about 90 minutes after the earthquake.
01:41Despite this considerable time lapse,
01:43neither the inhabitants nor the tourists are prepared.
01:46Many are those who, intrigued by the unusual receding of the sea,
01:50go to the beach to observe the phenomenon
01:52before being submerged by a water wall.
01:55That day, nearly 5,400 people,
01:58including 2,000 foreign tourists,
02:00will lose their lives in Thailand.
02:01An hour after hitting Thailand,
02:04the tsunami hit southeast India, near Chennai.
02:07Waves loaded with debris sink several kilometers into the land,
02:11taking more than 10,000 lives.
02:13In Sri Lanka, the situation is even more dramatic.
02:16More than 30,000 people succumb,
02:18while hundreds of thousands others find themselves homeless.
02:22The exceptional power of the tsunami
02:25even manifests itself at a considerable distance.
02:28Eight hours after the earthquake,
02:30it makes its last victims in South Africa,
02:338,000 kilometers from the epicenter.
02:35There, unpredictable waves take the swimmers by surprise.
02:40The workers of the National Tsunami Alert Center
02:43attribute the magnitude of this destruction
02:45to the extraordinary power of the earthquake.
02:47It is the result of a subduction fault
02:50where dense oceanic plates slide
02:52under lighter continental plates.
02:55These faults, among the largest in the world,
02:57are located under the oceans.
03:00The 2004 earthquake
03:02fractured an area of 1,500 kilometers
03:05between the Indian and Australian plates,
03:07at a depth of 50 kilometers under the seabed.
03:10In addition, instead of limiting itself to a brief shake,
03:13the earthquake lasted 10 minutes,
03:15releasing a colossal energy.
03:17During this period of time,
03:18huge portions of the ocean floor rose 40 meters,
03:22a movement of a prodigious magnitude.
03:24This sudden movement generated gigantic waves
03:27that spread across the ocean,
03:29similar to the circles formed by a galley launched into the water.
03:33However, the tsunami waves
03:35are nothing like those of the surfers.
03:38These waves look more like a tumultuous river,
03:42submerging everything in its path.
03:44Being caught in these waves
03:46almost makes any chance of survival illusory.
03:49If the currents don't drag you under the surface,
03:51the debris carried by the waves will.
03:54This explains why, during earthquakes,
03:56there are many injured and the human losses are relatively small.
04:00On the contrary,
04:02tsunamis cause much more deaths than injuries,
04:04because surviving such a disaster is extremely difficult.
04:08Devastating tsunamis like the one in 2004 are rare,
04:12which explains why India and Sri Lanka
04:14did not have similar precedents.
04:17This lack of experience,
04:18associated with the absence of warning systems,
04:21has made the consequences even more dramatic.
04:23The populations, far from the epicenter,
04:26did not feel the earthquake.
04:27Deprived of warning signs,
04:29official warnings or historical memories,
04:32they were taken for granted
04:34when the waves ravaged these densely populated coastal areas.
04:37The Pacific Ocean, the largest in the world,
04:40is the main theater of earthquakes and tsunamis.
04:43Locally destructive tidal waves
04:45hit this region every 1 to 2 years.
04:48Indeed, 76% of the recorded tsunamis
04:52occurred here.
04:53In addition,
04:5499% of the victims of tsunamis
04:57are linked to local or regional events,
05:00which occur more frequently
05:02and hit coastal areas
05:04with formidable speed.
05:06One question remains, however,
05:08could a tsunami as devastating as the one on December 26
05:11occur again?
05:13The answer is unfortunately complex.
05:15A warning system was put in place in the Indian Ocean
05:18to warn coastal nations of potential tsunamis.
05:22However,
05:23human behavior remains a major obstacle.
05:25This was illustrated in a magnitude-of-nature test in 2012,
05:29when many inhabitants of Banda Ase,
05:32in Indonesia,
05:33ignored the evacuation towers despite a tsunami warning.
05:36It seems that the experiment is not always enough
05:39to anchor the right reactions.
05:40The Indian Ocean warning system
05:43is based on underwater pressure sensors
05:45located near tectonic faults.
05:47These sensors record variations
05:49and transmit data to surface buoys,
05:52which then relay this information by satellite
05:55to ground control centers.
05:58Authorities analyze the data
06:00and decide whether alerts should be issued
06:02or whether evacuation must be pronounced.
06:05Ase,
06:06located on one of the most active faults in the world,
06:09has adopted additional security measures.
06:12Sirens have been installed in coastal cities,
06:15inhabitants receive alerts on their phones,
06:18and reinforced concrete evacuation towers,
06:20capable of sheltering 500 people,
06:23serve as a specially designed security zone
06:25for emergency situations.
06:27To assess the preparation of the populations,
06:30authorities organized an evacuation exercise in 2009.
06:3418 countries in the Indian Ocean
06:36participated in this simulation of a powerful earthquake,
06:39mobilizing thousands of coastal communities,
06:41and the officials concluded to the success of this exercise.
06:44The first real test of the system took place in April 2012,
06:49when a magnitude 8.6 underwater earthquake
06:52to the west of Ase triggered tsunami alerts.
06:55Although no significant wave was formed,
06:58this event highlighted major shortcomings.
07:01Many inhabitants ignored the evacuation towers
07:03and chose to flee by car or motorcycle,
07:06causing huge traffic jams in the city.
07:08This left some people stuck in areas at high risk in the event of a tsunami.
07:13The situation was chaotic,
07:14to the point that some even decided to return to the beach
07:18in search of signs of a tsunami.
07:20A very serious mistake.
07:22There is still a lot to be done
07:24to improve the chances of survival in the event of a tsunami.
07:27What is essential, however,
07:29is to recognize the signs of a tsunami.
07:31This starts with violent earthquakes.
07:34Powerful earthquakes in coastal areas can trigger tsunamis.
07:39If you notice that the water on the beach is retreating at a disturbing speed,
07:43exposing the seabed, reefs and fish,
07:46leave immediately.
07:48Unusual sounds from the ocean can also be a warning.
07:53A loud and roaring noise,
07:55comparable to that of a train or a jet engine,
07:58can also signal the arrival of a tsunami.
08:01If you notice one of these signs,
08:03it is crucial not to wait for the official evacuation orders.
08:07Leave the lower areas immediately
08:09and head for higher ground.
08:12If you are at home,
08:13make sure that all members of your family are informed of the situation
08:17and follow the instructions of the authorities.
08:19Also keep in mind that local-origin tsunamis can strike in a few minutes,
08:24which requires a quick reaction.
08:26For a more distant tsunami,
08:28it is possible to have more time to evacuate.
08:31If you can't get far enough,
08:33find shelter in high concrete buildings.
08:37Avoid small buildings or dwellings located in low areas,
08:41where the risks are increased.
08:43If you are at sea, stay offshore,
08:45because tsunamis are less dangerous in deep water.
08:48It is therefore essential to avoid returning to the port
08:51when a tsunami alert is in effect.
08:53If you are already at the port,
08:55consult the port authorities to obtain instructions.
08:58And if you have the opportunity to head for deep waters,
09:02do so calmly.
09:03For small boat owners,
09:05it may be preferable to leave the boat and look for high-rise shelters.
09:09And, above all,
09:11prioritize your safety by gaining a higher ground rather than saving your property.
09:16For inhabitants of coastal areas,
09:17some precautions can be taken in advance to protect your property.
09:21Since the majority of tsunami waves are less than 3 meters high,
09:25you could consider raising your house to limit the damage.
09:29You can also consult an engineer to assess its strength
09:33and reinforce it if necessary.
09:36Finally, do not forget to secure the dependencies
09:39and install fences that will allow animals to take shelter in high places.
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