Nankai Trough Quake Advisory Guidelines to Be Revised; Restrictions on Railway Service Will Not Be Required

The Yomiuri Shimbun

20:00 JST, July 25, 2025

Railway operators will not be asked to limit services when an advisory is issued over potentially heightened risk of a Nankai Trough earthquake, the Cabinet Office has revealed.

A draft revision of guidelines for the Nankai Trough Earthquake Extra Information, as the advisory is known, will state that railway operators will not be asked to impose service restrictions, the Cabinet Office revealed at the first meeting of an expert panel held on Thursday. The Cabinet Office intends to finalize the revision as early as next month.

The guidelines, first drawn up in 2019 when the extra information advisory system was introduced, spell out the actions residents, businesses and others should take when an extra information advisory is issued because the probability of a Nankai Trough earthquake has increased.

However, the document offers scant detail on how to respond to the Nankai Trough Earthquake Extra Information advisory with the keyword Megathrust Earthquake Attention, which is issued when an earthquake of magnitude 7 or greater has occurred in a relevant area.

When the advisory was first issued on Aug. 8 last year after a quake in the Hyuganada Sea off Miyazaki Prefecture, responses differed nationwide and confusion arose. Some railway companies suspended services or operated trains at reduced speed.

In response, the Cabinet Office now plans to flesh out the guidelines’ section on the Megathrust Earthquake Attention advisory and to state explicitly that railway companies will not be required to restrict their operations. The revision will also incorporate case studies — such as events that went ahead last August after evacuation sites and routes had been publicized in advance.