Government Tsunami Warning Systems

Instructions: Review the animation and images below and then scroll down to answer the questions that follow.

The National Oceanographic and Atmospheric Administration has deployed a series of Deep Ocean Assessment and Reporting of Tsunami (DART) buoys in the Pacific Ocean as part of their system to detect the deadly waves.

Sensors on the sea floor relay suspicious pressure changes to a surface buoy, which sends the data to NOAA's tsunami warning centers. Scientists analyze the information, and issue tsunami alerts to authorities in threatened areas. Click 'play' to see the animation

Yellow dots mark the location of existing DART buoys. Red dots are buoys proposed for an expanded tsunami monitoring system.

Many Pacific coast communities have developed tsunami educational programs and emergency plans.

Questions

Now, answer the questions below.

1. There are a lot of waves in the ocean - how can the DART sensors tell the difference between an ordinary wave and a tsunami?
   Check Answer
   Ordinary wind waves disturb only a very thin layer of water at the surface of the sea, and so don't affect the sea floor far, far below. Tsunami move the entire water column, which in the open sea is thousands of meters thick. So when a tsunami rolls over a sensor on the sea floor, it will cause a noticeable change in water pressure.
2. Why do you think NOAA's DART buoys were originally placed just in the north and central Pacific? Suggest some geologic and political reasons for the planned expansion of the system and the placement of the extra buoys.
   Check Answer

   The Pacific Ocean is the site of violent geologic events. Its edge is called the Ring of Fire, because it is lined by active volcanoes. Strong earthquakes are common. All this tectonic activity makes tsunami more frequent in the Pacific than in the Atlantic. And countries on the North Pacific rim, like the United States and Japan, had the financial and technological means to develop, install, and maintain a system of warning buoys.

   Since these sensors were put in place, geologists have learned that the east coast is also vulnerable to tsunami, mainly due to enormous undersea landslides. And the 2004 event made it clear that the humanitarian and financial costs of tsunami in other parts of the world justify expanding the system to cover even those countries that cannot pay to participate.

3. The tsunami warning buoy system was established to help give people time to evacuate before a tsunami strikes. But are these warnings always going to come in time? Explain.
   Check Answer
   Some people will not be warned in time to evacuate. In the current NOAA Tsunami Early Warning System, sensors must register an earthquake or change in water pressure and alert the warning centers, then scientists have to study the data, determine who is at risk, and notify the authorities, and then officials warn the public. All this takes time. But people closest to the source of a tsunami may be hit only a few minutes after the earthquake or eruption, long before warnings can be issued.