According to Time.com, Japan has one of the most advanced early earthquake warning systems in the world. The system was launched in 2007 and detects tremors, calculates an earthquake's epicenter and sends out short warnings from over 1,000 seismographs spread throughout the country. The system is run by the National Research Institute for Earth Science and Disaster Prevention, but the Japanese Meteorological Agency sends out the actual warnings.
Along with the early warning system, many private offices and factories employ their own early-warning systems. For instance, Japan Railways launched their own private earthquake detection system in the early 1990s after the introduction of the Nozomi bullet train.
The Japan Meteorological Agency states that the early warning system is intended to mitigate "earthquake-related damage by allowing countermeasures such as promptly slowing down trains, controlling elevators to avoid danger and enabling people to quickly protect themselves in various environments such as factories, offices, houses and near cliffs." However, there are also several limitations of this system. These include timing, false alarms, magnitude estimation and seismic intensity estimation. For example, the amount of time between the early warning and the arrival of the earthquake is not very long. In certain instances, areas that are close to the epicenter of the quake may not even receive the warning before the tremors hit.