The ocean-based tsunami detection system, known as the deep-ocean assessment and reporting of tsunamis (DART), which today sent warnings to residents on the west coast of the United States and Hawaii (as well as more than 50 other countries) is an unreliable system, according to 2010 report. Of the 39 stations deployed in 2008 only an estimated 60% were operational by 2009 (click here to see current active and inactive stations). The report, issued by the National Research Council of the National Academy of Sciences, concluded that the buoy stations, despite their technological achievements, may not be a feasible long term solutions for providing improved early warning and real-time reporting of tsunamis.
     "The technology is good, but it's designed for distance events like today," says Nathan Wood, a research geographer at the U.S. Geological Survey and a member of the committee that issued the report. The massive 8.9-magnitude earthquake hit off the coast of Japan, giving residents of the United States enough time to prepare or evacuate. Tsunamis are capable of hitting earthquake stricken areas 15-20 minutes after the earthquake itself. But it takes several minutes for researchers at tsunami warning centers to gather seismic data, run models, and issue warnings. Having already lost about seven minutes, for example, those close to the epicenter have little time to evacuate or mobilize before the tsunami strikes, says Wood. Information from the buoys is utilized, roughly, anywhere from 10-60 minutes after an earthquake to confirm a tsunami event and determine the size of the waves. "There is just not time for warnings when a local event occurs."
     The DART system was developed by the National Oceanic and Atmospheric Administration in 2001. It consists of a bottom pressure recorder anchored to the seafloor and a moored surface buoy. Data from the pressure recorder is transmitted to the buoy via an acoustic link, and the buoy sends the data to a satellite that communicates with a control station. Most of the buoys are located in the Pacific Ocean where a tsunami landfall is thought to be more likely. Other locations include the Atlantic Ocean and Carribean.

     Wood says the main problem with the buoy stations is that they are hard and expensive to maintain, and because they are located in a rather harsh environment, they have a fairly high failure rate. One trip to fix a failed buoy could cost $25,000. Each station was designed to be operational for at least four years, but after just one year, 2006, nearly 20% of the buoys were inoperable. The NRS/NAS report stated that at some points in time 30% or more of the buoys have been inoperable.

     Another issue is that there is no "failure analysis effort", says Wood. When the systems go offline it's difficult to figure out why. And if one station becomes inoperable there is just no coverage in that area.
     The report recommends that NOAA conduct a cost-benefit study and develop alternative methods. Wood says that while the technology is valuable and can be effective, the financial constraints of maintaining the stations might make them an unsustainable long term solution.
     What could make them better, he suggests, is if the system could expand beyond just scientist getting information via instant or text messages to people that need it to save lives or take action. He adds that the buoy systems could be financially sustainable if they were used for more than just tsunami warnings.

     The world's only earthquake warning system likely helped limit damage and loss of life.
Will Knight 03/11/2011
     The earthquake that struck Japan early this morning was the worst seen in that country for over 300 years (with a local magnitude of 8.9). Hundreds have been killed and injured so far, but the loss of life was likely limited by two vital early warning technologies: a new earthquake alert system, and ocean-based tsunami warning system.
     The earthquake warning system, which has never been triggered before, automatically issued alerts via television and cell phones shortly after the first, less harmful, shock wave was detected, providing time for many people to prepare for the more powerful shock wave that followed. It also caused many energy and industrial facilities, and transportation services to shut down automatically. A string of detection buoys in the Pacific Ocean detected the tsunami that resulted from the earthquake, sending warnings of possible catastrophe to many different nations.

     The graphic above shows the stages involved with triggered Japan's earthquake warning system. Further information can be found at this page of the Japan Meteorological Agency.

     This image shows the location of detected seismic activity, and its severity (Japan uses a different scale for measuring the intensity of earthquakes). Further information here.

     The graphic above shows how the Deep-ocean Assessment and Reporting of Tsunami (DART) tsunami buoys work.

     The image above shows the location of tsunami buoys across the Pacific, and which buoys have been triggered (the larger yellow diamonds). Live information can be found in this page at the National Oceanic and Atmospheric Administrations National Data Buoy Center.
     Updated 14:30 EST: NOAA has published a page dedicated to the tsunami event.

     The image above was generated using the method of splitting tsunami (MOST) model. It uses data collected by tsunami buoys to estimate the wave arrival time and the wave height of the tsunami.

     Power outages and fires have been reported at multiple plants, and radiation leaks are possible.
Kevin Bullis 03/11/2011

     The massive 8.9 magnitude earthquake in Japan reportedly forced the automatic shutdown of 11 nuclear reactors at four plants in the northeastern part of Japan near the earthquake's epicenter. There have been no reports of radiation leaks, although Japanese news organizations are reporting that the radiation level within one of the plants is rising, and that radioactive steam may be released to reduce pressure buildup in the facility. [Update: Japan's nuclear safety agency reportely says the amount of radiation would not threaten human health.]
     The earthquake cut off power to at least one of the nuclear plants, the Fukushima plant, and backup generators failed after an hour, forcing local governments to bring in mobile generators. Even after an automatic shutdown, the reactors must be cooled—and without power, cooling water cannot be circulated. [Update: A backup cooling system that uses batteries can temporarily delay overheating.]
     There have been reports that enough water remains in the reactors for cooling, and to prevent the nuclear fuel from being exposed. The U.S. State Department has said that the U.S. is bringing coolant to the plant, though Jasmina Vujic, a professor of nuclear engineering at the University of California at Berkeley, says it's not clear why that would be necessary, unless ordinary clean water—which is all that's needed for coolant--is unavailable. [Update: reports that the U.S. sent coolant may have been incorrect.]
     A fire in one of the non-nuclear buildings at another power plant has reportedly been extinguished.
     Nuclear power plants in Japan are engineered to withstand "extremely large earthquakes," and have survived major earthquakes in recent years, Vujic says. She says they have "several layers of safety." These include concrete walls comprising a total of nearly 20 feet of concrete between the reactor and the outside, and five and a half inches of steel.

     The reactors shut down automatically by inserting control rods into the reactor; the rods absorb neutrons and immediately stop the fission chain reactions inside the reactor.
     Although no radiation leak has been confirmed, nearly 3,000 people near the Fukushima plant have been evacuated as a precaution.