The problems presented by the physical geography of Japan that led to the construction of underground railways were the number of earthquakes that presented its geography because of its location in the Pacific Ring of Fire. Japan is a highly seismic country due to earth tremors that are frequent and occasional volcanic activity.
Building underground railroads solved the problems presented by the physical geography of Japan by uniting the islands of Hokkaido and Honshu of Japan. Opened in 1988, it runs a hundred meters under the sea floor and is located 240 meters below sea level.