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Amateur Footage Helps Us Understand Tsunamis More

December 26, 2004. The day of the worst tsunami in living memory that pummeled Indonesia and shocked the world. It was the first major tsunami that took place after mobile phones with cameras were created, and people around the world were able to witness the catastrophe through the shaky videos. But this footage was useful for more than that. Video footage helped scientists to understand tsunamis more. Here's how. 

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  • gif of tsunami wave beginning to rise in japan
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    Before the 2004 tsunami - which was a result of an earthquake in the Indian Ocean - the ways that scientists gathered information about tsunamis was done roughly and with a lot of estimation. Scientists would rely on measurements of the water marks on buildings with measuring tapes, examine the debris to guess how far it had traveled, and ask eyewitnesses questions about which direction the water came from, how quickly it moved, if there were any waves, and how deep the water became. 

    These methods, especially questioning eyewitnesses, are not particularly reliable, but they were the only tools that scientists could use at the time. As a result of this, there was little understanding about how tsunamis behaved, meaning that there was little to no warning before a tsunami hit land. 


  • gif of tsunami water getting higher in river
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    In the aftermath of the 2004 tsunami, videos emerged from Sri Lanka and Indonesia (mainly from tourists). Most of the videos were too chaotic as people ran for their lives, but a few videos managed to capture the water moving in as they filmed from high, safe places. From these videos, scientists can view the actual depth of the water from footage of the water flowing through streets. They also survey the locations in the video, calibrating the perspective and the motion of the camera. 

    The result was a more precise measurement of how fast the water moved when it reached residential areas. When comparing this information to that gathered in the previous method, it appears that eyewitnesses seriously underestimate the speed of the water when just looking at it. This information is highly valuable to scientists. 


  • gif of 2011 japan tsunami breaking over wall
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    Another discovery made by the footage of tsunamis was that while normal waves slow down when the hit dry land, tsunami waves actually accelerate when they approach land. This was information that no eyewitness had ever noticed. 

    As smartphones and technology became more advanced, by the time the 2011 tsunami hit Japan, scientists were able to gather more data than ever before about tsunamis. Scientists would go back to the location where people filmed their videos and use a terrestrial laser scanner (LIDAR) to create a digital map of the landscape. Then, they'd superimpose the real life scan onto the video of the location under water to find out how fast the water moved. 

    They could even isolate a piece of debris to determine its speed and the pattern of the flow of water, and how quickly a human would have to run to be out of danger's way. The scientists found out that for powerful tsunamis like the 2011 tsunami in Japan, people would have to run as fast as Usian Bolt to outrun the tsunami, which is 27.8 miles per hour - the average adult runs at around 15 miles per hour.


  • gif of 2004 tsunami filmed in india
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    The advent of tsunamis being filmed marked a change in the technology that could warn people about an incoming tsunami. The images from videos help scientists confirm the accuracy of the computer programs that predict when a tsunami will hit. Deep-ocean Assessment and Reporting of Tsunamis (DART) buoys are another tool for warning of oncoming tsunamis, 60 of which are located in the world's oceans today. 

    By combining these two means, as well as the data from seismometers, scientists have a much deeper understanding of tsunamis than they did twenty years ago. This means that they are more well-prepared to warn people of a potential tsunami - and save more lives.


  • gif of 2004 tsunami in india
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    So if you happen to be caught in a tsunami, after ensuring your safety, take a video if you can! It'll be more than a viral video for your Instagram feed. It could help scientists to save more lives. 

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