A powerful earthquake struck the northeastern coast of Japan at 2:46 p.m. 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. More than 4,000 Seismic Intensity Meters provide information within two minutes of an earthquake happening.  There are also concrete sea walls around much of the Japanese coastline. But these measures proved no match for the powerful earthquake and tsunami.  Costas Synolakis is a tsunami expert in the University of Southern California in Los Angeles. He says: "Japan is one of those most well-prepared countries on earth in terms of tsunami warning. They had a warning. I think what went wrong is that they had not anticipated the size of this event." He says there are two reasons for this. First, scientists had not expected such a large earthquake. The 9.0 magnitude earthquake was the 4th most powerful earthquake ever recorded worldwide. It was also the worst ever to hit Japan. The tsunami waves reached as high as 13 meters in some areas. Second, Japan's concrete sea walls were not built to handle such high waves.  " In Sendai , they were about three meters. At least in that area they were not expecting such a sizeable wave because they would have built a higher seawall."  A tsunami wave can travel as fast as 800 kilometers per hour. To get to 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. The tsunami waves followed almost immediately. Experts say early warning systems will continue to be limited by these facts until earthquakes and tsunamis can be predicted. According to Costas Synolakis,   _  .
Japan had a warning of such a serious earthquake Japan has experienced the worst earthquake worldwide the Japanese should have built higher seawalls The Japanese were not really prepared for such a disaster