Japanese tsunami alert system proves itself after recent earthquake

It is no accident that the word we use to describe a massive tidal wave comes from Japan. That island nation has long suffered from tsunamis (“harbor waves”), the result of sitting on a geological shelf that accounts for about 20 percent of the world earthquakes measuring six or higher on the Richter scale. Fortunately, Japan is among the most technologically sophisticated of nations, and its computerized Earthquake and Tsunami Observation System (ETOS) is among the most sophisticated in the world.

Although a recent earthquake in Japan led to waves only sixteen inches high, the event has once again proven ETOS’s worth, and it validated changes made after a 1993 tsunami struck a small island off Hokkaido before warnings could be issued. Although hardly any Japanese felt the 8.1 magnitude earthquake, anyone watching television saw a tsunami warning almost instantly and thousands took to higher ground immediately. (The alerts themselves rely on a strong cooperation between the government and the television industry. Not only can the weather service preempt any programing to issue a tsunami warning, it can even turn on televisions to do so.)

Like similar systems worldwide, ETOS relies on a complement of 180 seismic stations across Japan and about 80 water-borne sensors to provide real-time data twenty-four hours a day. The system has a baseline goal to issue tsunami alerts within three to five minutes after a quake that occurs in or near Japan, though this is not always possible if, as was the case earlier this month, the epicenter is outside the system’s immediate range. In the recent case, where the earthquake struck off the Russian Kurile Islands, it took fourteen minutes to issue the alert.

-read more in George Nishiyama’s Scientific American report