FEATURE
USING EXISTING SUBMARINE CABLES AS A TSUNAMI WARNING NETWORK BY GEOFF BENNETT
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2015 United Nations report estimated that every year, an average of 60,000 people and $4 billion USD in assets are exposed to the global tsunami hazard, which can be triggered by certain types of undersea earthquakes or volcanic eruptions. Many of us will remember the horrific events of Boxing Day 2004, when the Sumatra-Andaman undersea earthquake triggered a tsunami that resulted in the deaths of almost a quarter of a million people in 14 different countries. The world has a number of different earthquake detection systems deployed or in development today: • Land-based detectors are the backbone of seismic detection, but as the name suggests they can’t always be located close to potential seismic subsea zones. • Ocean-based Deep-ocean Assessment and Reporting of Tsunamis (DART) buoys are an excellent solution, but there are very few of them, and they are frequently out of action because of harsh conditions or even vandalism. • The SMART (Science Monitoring And Reliable Tele-
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communications) Cables initiative includes seismic, pressure, temperature, and acoustic sensors that can be installed in adapted subsea repeater modules, or even in separate dedicated modules along the cable. But the first such cable will only be ready in 2025, and the rollout of subsequent SMART Cables could be slow. One of the obvious factors in early warning is that the closer a detector is to the epicenter, the earlier the warning can be to those in danger. For every 200 km the detector is from the epicenter, there is an additional one minute of delay for a potential warning of an impending tsunami. The SubTel Forum database shows there are 444 submarine cables around the world today. What if we use the existing submarine cables, adding something to them that would allow them to be used as a detection network? While they may not be as capable as SMART Cables that are specifically designed for seismic detection, they have the benefit of being in place already.