Researchers in Japan, one of the world's most earthquake-prone countries, have developed a system that can provide several seconds' warning that violent shaking from a violent earthquake is about to commence.The system, coordinated by the Japan Meteorological Agency (JMA), is expected to go into full operation later this year and ties together advanced sensing technology with fast data processing and advanced telecommunications networks.Earthquakes generate two main types of waves, called primary waves (P-waves) and secondary waves (S-waves). The P-waves travel at about twice the speed of the S-waves and are typically weaker. By quickly detecting, measuring and analyzing the P-waves from a network of sensors, the earthquake's source and strength can be estimated. This data can then be used to predict when the potentially destructive S-waves will be felt and how strong they will be.The system could provide anything from a few seconds to a minute's warning of a major earthquake - long enough to bring trains to a halt, cut gas supplies and stop factory production lines. How much warning people have will depend on how far they are from the earthquake, so locations nearer the epicenter, which are likely to be shaken the most, will get the least warning. But researchers agree that any warning is better than none.The JMA, which maintains a network of about 200 earthquake monitoring stations across Japan, is already supplying test data, and several companies have developed systems for use in homes and offices that use the JMA's data to generate warnings.One of the simplest comes from Tecs, which developed software that can be installed inside several models of Canon office photocopier. The software uses the copier's network connection to maintain an Internet link with a server containing data about potential earthquakes from the JMA. When an earthquake is about to occur, the software can sound an alarm and also flash up warnings on PCs connected to the office network, so long as they have a companion software application installed, said Shouji Nihei, a company employee who was demonstrating the system at last week's Earthquake Technology Expo in Yokohama, Japan.Slightly more complex is a system from Meisei Electric, a major manufacturer of earthquake sensors. The Meisei system uses a dedicated PC connected via a leased line or VPN connection to guard against any delays in receiving information. In addition to warnings on PC screens, the system can flash warnings on up to 16 small display units that a company could install throughout its office or factory, said Michio Neriki, deputy general manager of Meisei's disaster prevention systems business unit.Meisei has estimated how much warning its system would deliver in the event of a big earthquake occur off the coast of central Japan - an event that has been long predicted. The so-called Tokai quake is expected to kill between up to 10,000 people and injure tens of thousands more.The shaking would likely cause considerable damage to buildings in Shizuoka, the city nearest the expected quake, and Meisei estimates it would have up to 10 seconds warning. In Tokyo, about 200 kilometers away, damage is also expected, but the system could provide up to 40 seconds warning, the company estimates.IPv6 is being put to use. NTT East, the local telephone carrier in Tokyo, has developed an IPv6-based system that uses multicasting technology to broadcast the data to cut down on Internet delays. A prototype has been built into a video phone designed for use inside homes.Interest in earthquake preparedness jumped in Japan after a strong quake killed more than 6,000 people in Kobe in 1995, but in the years following the interest waned. This changed in the last few years after a series of strong quakes rocked the country and brought the danger to people's minds again.Companies have also been reacting after seeing reminders of the damage earthquakes can cause. An earthquake in October 2004 caused about \u00a587 billion in damage to a Sanyo plant in the area and forced the company to report a loss for the year.The new system is already working on a trial basis in a semiconductor factory operated by Oki Electric in Miyagi prefecture, northern Japan. The system has been installed since September and should shut off the supply of hazardous gases used in chip production in the seconds before shaking from a strong quake begins. Since it was installed there have not yet been any quakes strong enough to trigger a shut-down.