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Calculating 'quakes faster than a bullet
About 10% of the world's earthquake energy finds its release in Japan - creating a built-in hazard for rail companies operating the country's bullet trains.
Central Japan Railways which is in the process of introducing the new 300km/h Series N700 Shinkansen (pictured above) to the Tokyo-Osaka route, is using the occasion to also install a new early warning earthquake detection system.
The new system, known as TERRA-S, will shave a crucial second from the time needed to automatically halt the speeding Shinkansen if the detector has calculated that an earthquake is about to send a tremor across the train's path.
The previous early warning system was designed to sense an earthquake's destructive S-waves.
The new system will pick up the earthquake's faster-travelling P-waves ("primary" longitudinal waves) soon after they leave the epicentre.
The old detector swang into action three seconds after an S-wave started sweeping out from the epicentre while the new detector will react in two seconds.
A company spokesman said in the 13 years the old S-wave detectors were in place, trains were stopped - but no resulting earthquakes were strong enough to actually damage the Shinkansen lines. The new detector is costing $8.4 million.
According to CJR, normal operating speed for the Shinkansen is 270km/h. After TERRA-S automatically cuts power to the train's nearest substation, it would take about 90 seconds for the Shinkansen to come to a stop. In the meantime the train would have travelled approximately 4km.
