The Meteorological Agency plans to expand its service of supplying information on the arrival time of major earthquake jolts. It is now supplying such information to about 230 businesses. For example, the information is used to ensure safety in railway operations and construction sites. The general public will start receiving the service in spring, mainly through broadcasts. People should be educated about the new service so they can use it effectively and wisely.
When an earthquake occurs, preliminary tremors, which are vertical shaking transmitted by P waves, first arrive, followed by strong, horizontal jolts transmitted by S waves. The new service takes advantage of the time lag between the two sets of waves. If an expected intensity of an earthquake is five or stronger in the Japanese scale of seven, the agency issues emergency reports.
Even with the new service, people will have less than a minute to prepare. In the case of a large-scale earthquake off the Tokai region, the service is expected to give a preparation time about 10 seconds to people in Shizuoka. But a simulation shows that this can enable an 81 percent reduction from a maximum 9,200 deaths predicted by the government’s anti-disaster white paper for Shizuoka Prefecture. But when the focus of an earthquake is located directly below an area to be affected, the service will not work since P and S waves arrive almost simultaneously. The agency also hopes to issue tsunami warnings within two minutes of the occurrence of some types of earthquakes.
To help prevent panic, the government and other organizations need to teach the people in advance what actions they should take and should not take when they receive the emergency reports.
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