From the TWS, the first warning is based purely on such seismic data. But once the big wave starts rolling it will have an effect on the level of the sea, itself, which is routinely monitored by weather stations of many types. This additional data gives a better idea of how bad the wave is really going to be, so in the TWS system, it is used to justify expanding

<http://www.pbs.org/cringely/pulpit/pulpit20041230.html> PBS: I, Cringely -- The Pulpit How to Build a Global Internet Tsunami Warning System in a Month By Robert X. Cringely A friend of mine is missing in southern Asia. She isn't missing in the sense that anyone saw her swept away by this week's horrible tsunami, but she and her entire family haven't been heard from, either so of course, I am worried. That worry makes real for me a disaster of such horrific proportions that without a personal connection, it simply can't be real to most of us. By the time all the bodies have been counted and estimated, probably 100,000 people will have died. If cholera follows, as it tends to in that part of the world, another 40,000 or more could follow. That's a lot of people, 140,000 -- enough people that we ought to do something to make sure it doesn't happen again. So of course, there is lots of talk about tsunami warning systems and global cooperation, but I think that's just going about solving the problem the wrong way. We don't need governments and huge sensor arrays to warn people on the beach about the next huge wave approaching at 400 miles-per-hour. Thanks to the Internet, we can probably do it by ourselves. Here's the problem with big multi-government warning systems. First, we have a disaster. Then, we have a conference on the disaster, then plans are proposed, money is appropriated, and three to five years later, a test system is ready. It isn't the final system, of course, but it still involves vast sensor arrays both above and below the surface of the ocean, satellite communication, and a big honking computer down in the bowels of the Department of Commerce or maybe at NASA. That's just the detection part. The warning part involves multilateral discussions with a dozen nations, a treaty, more satellite communication, several computer networks, several television and radio networks, and possibly a system of emergency transmitters. Ten years, a few million dollars and we're ready. We can't rely on governments to do this kind of work anymore. They just take too darned long and spend too much money for what you get. Besides, since governments are almost totally reactive, what they'll build is a warning system for precisely the tsunami we just had -- a tsunami bigger than any in that region since the eruption of Krakatoa in 1883. One could argue (and some experts probably will) that it might even be a waste of money to build a warning system for a disaster that might not happen for another 121 years. What we need is a tsunami warning system not just for parts of Asia, but for anywhere in the world that might be subject to such conditions. And that decision about what beaches to protect ought to come not from Washington, D.C., or Jakarta, or any other capital city, but from the beach people, themselves. If you are concerned about a giant tidal wave taking out your village, it might be a good idea to build your own warning system, you retired engineer, you Radio Shack manager, you harbor master, you radio amateur, you nerd with a suntan. It can be done. The Tsunami Warning System (TWS) in the Pacific Ocean shows us how such a warning system can be run with the cooperation of 26 countries. Maybe we can do the same thing, just without all that cooperation. TWS is based on crunching two kinds of data -- seismic activity and changes in sea level measured by tide gauges. Most tsunamis begin with an earthquake, the severity and epicenter of which can tell a lot about whether a tsunami is likely, how strong it will be, and in what direction it is likely to go. the warning to other communities beyond those warned purely on the basis of seismic data. Depending on where the originating earthquake is, the tsunami can be minutes or hours from crashing into a beach. This week's wave took about 90 minutes to reach Sri Lanka, just over 600 miles from the epicenter. That not only means the wave was traveling at over 400 miles-per-hour, it also means that had a warning system been in place, there would easily have been time to get the people who were affected in Sri Lanka to higher ground. So to start, we need raw seismic data. If you take a look at the fourth of this week's links, you'll see that plenty of such data are available. Thanks to the Pacific Northwest Seismograph Network, here is one place where you can find real time data from 199 seismographs around the world. There are also links to a dozen regional operations that consolidate such data. The data is available. Tide gauge data is available, too, though there is less of it, and aggregation will require more effort, so I say let's just stick to seismic data for our warning system. Here's where we need the help of a tsunami expert, someone who can help us calculate the size and direction of a likely tsunami based on the available seismic data. Fortunately, there has been quite a bit of work done in this area of study (see link #5), and appropriate computer codes that can be run on a personal computer either exist or can be derived, perhaps by reflexively evaluating seismic data from known tsunami events. But remember that what we care about here is not global tsunami warning but LOCAL tsunami warning (Is it going to hit MY beach?), so the required seismic data sources can pretty easily be limited to those with an uninterrupted aspect of the target beach, which means half a dozen seismographs, not 199. Since the basic question is fairly simple -- "Is my beach going to be hit by a destructive tsunami and when?" -- and the required data sources are limited, I figure we won't need a supercomputer. The seismographs are online, we gather the data using XML, continuously crunch it using the codes I am assuming already exist, then we need the warning, which I would flash on the screen of my PC down at the surf shop using a Javascript widget built with Konfabulator, the most beautiful widget generator of all. Looking just like a TV weather map, the widget would flash a warning and even include a countdown timer just like in the movies. You don't need an international consortium to build such a local tsunami warning system. You don't even need broadband. The data is available, processing power is abundant and cheap. With local effort, there is no reason why every populated beach on earth can't have a practical tsunami warning system up and running a month from now. That's Internet time for you, but in this case, its application can protect friends everywhere from senseless and easily avoidable death. -- ----------------- R. A. Hettinga <mailto: rah@ibuc.com> The Internet Bearer Underwriting Corporation <http://www.ibuc.com/> 44 Farquhar Street, Boston, MA 02131 USA "... however it may deserve respect for its usefulness and antiquity, [predicting the end of the world] has not been found agreeable to experience." -- Edward Gibbon, 'Decline and Fall of the Roman Empire'