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This is the VOA Special English Technology Report.

A powerful earthquake struck the northeastern coast of Japan at 2:46 PM local time on March 11th. Japan's Meteorological Agency released its first tsunami warnings just three minutes later.

The country has one of the best earthquake early warning systems in the world. There are more than 4,000 sizemic intensity meters in place throughout Japan to measure earthquake activity. These meters provide information within two minutes of an earthquake happening. Information about the strength and the center of the earthquake can be learned within three minutes.

There are also Concrete Seawalls around much of the Japanese coastline. But these measures proved no match for the powerful earthquake and tsunami.

CS is a tsunami expert with the department of Civil and Environmental Engineering at the University of Southern California in Los Angeles.  

CS: “Japan is one of the most well-prepared countries on earth intentional even tsunami warnings. They had a warning but I think what was wrong is that they had not dissipated even the size of this event.”

He says there are two reasons for this. Japan has not had any event anywhere near as big as this one in the last 150 years. And scientists had not expected such a large earthquake happening off the coast of Japan.

The 9.0 magnitude earthquake was the forth most powerful earthquake ever recorded worldwide. It was also the worst earthquake ever to hit Japan.

The tsunami waves that followed were reported to have reached as high as 13 meters in some areas. CS says Japan's Concrete Seawalls were not built to handle such high waves.

CS: “The Concrete Seawalls in many places in Japan are about 7 meters, which is about 33 feet. In Sendai, they are about 3 meters, which is about 10 feet. So that is so usered at least not all area they were not expecting such a sizeable wave.”

A tsunami wave can travel as fast as eight kilometers per hour. To get a higher ground, people would often have to travel for many kilometers. This can take more time than a fast traveling tsunami will permit. This is especially true in cases like Japan, where the centre of the earthquake struck so close to the coastline. The tsunami wave followed almost immediately.

Experts say early warning systems will continue to be limited by these facts until the earthquakes and tsunamis can be predicted.

And that’s the VOA special English Technology Report, written by June Simms. You can find more news about the disaster in Japan at our website voaspecialenglish.com. You can also find transcripts, MP3s and Podcasts of our reports. And you can find us on Facebook and YouTube at VOA Learning English. I’m Steve Ember.