Abstract
It is important for high-speed trains to early slow down and stop in the event of an
earthquake. Shinkansen system is equipped with an earthquake early warning (EEW) system
that transmits warnings based on seismometer observations. In recent years, an ocean bottom
seismometer (OBS) observation network has been installed offshore in the Pacific Ocean.
Subduction-zone earthquakes, such as the 2011 off the Pacific coast of Tohoku Earthquake,
may be detected earlier if OBS can be utilized for the EEW system. Therefore, we developed
a method to utilize OBS for the EEW system, in which we proposed a method of setting an
OBS threshold value and a method of preventing false warnings. Furthermore, we evaluated its
intended effects. The East Japan Railway Company started utilizing OBS in the Boso offshore
area in November 2017, and in the offshore area between Ibaraki and Kushiro in January 2019.
