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This is the VOA Special English Technology Report.
A powerful earthquake struck the northeastern coast of Japan at 2:40 PM local time on March 11th. Japan's meterological agency release its tsunami warning just 3 minutes later. Country has one of the best earthquake early warning system in the world. There are more than 4,000 seismic intensity meters in place through out Japan to measure earthquake activity. These meters provide information within 2 minutes of an earthquake happening. Information about the strength and the center of earthquake can be learned within 3 minutes.
There are also concrete seawalls around much of Japanese coastline. But these measures proved no match for powerful earthquake and tsunami.
** is a tsunami expert with the Department of Civil and Environmental Engineering at the University of Southern California in Los Angeles.
Japan is one of the most well prepare countries on earthquake in terms of tsunami warnings. They had a warning. I think what was wrong is that they have not anticipated the size of this event.
He says there are two reasons for this. Japan has not had any events anywhere near as big as this one in the last 150 years. And scientists had not expected so large earthquake happening off the coast of Japan. The 9.0 magnitude earthquake was the 4th most powerful earthquake every recorded worldwide. If it was also the worst ever to hit Japan, the tsunami waves that followed were reported to have reached as high as 13 meters in some arears.
** says Japan's concrete seawalls were not built to handle such high waves.
The concrete seawalls in many places in Japan about 7 meters that it's about 33 feet. In Sendai, they were about 3 meters, that it's about 10 feet. So that shows you that at least in that area, they were not expecting such size of waves.
A tsunami waves can travel as fast as 8 kilometers per hour. To get to higher ground, people would often have to travel for many kilometers. These can take more time then the fast traveling tsunami will permit. This is especially true in cases like Japan where the center of earthquake struck so close to the coastline. But tsunami waves followed almost immediately.
Experts say early warning system would continue to be limited by this facts until earthquakes and tsunami can be predicted.
And that's the VOA Special English Technology Report written by June Simmis.You can find more news about the disaster in Japan at our website voaspecialenglish.com.You can also find transcripts mp3s and broadcasts of our reports.And you can find us on Facebook and U tube at voalearning english.I'm Steve Ember.
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