Earthquake Early Warning due to long-period ground motion

When a large-scale earthquake such as the Nankai Trough earthquake occurs, a large, slow and long-period shake with a long cycle (the time it takes to make one round trip) occurs. Such ground motions are called long-period ground motions.

Based on the degree of difficulty in human behavior during an earthquake targeting high-rise buildings, and the degree of damage such as movement or fall of furniture and fixtures, as determined by the Japan Meteorological Agency, the magnitude of shaking due to long-period ground motion is divided into four classes. It is an index divided into

Basic knowledge and explanatory videos on long-period ground motions are posted on the Japan Meteorological Agency website linked below.

Measures to prevent furniture from falling, moving, or falling are also very important as long-period ground motion measures. In particular, if the shaking is large, furniture etc. cannot be sufficiently fixed, and there is a possibility that the door will be blocked due to falling or collide with a window glass and fall to the ground. It is also important to consider the place where furniture is installed in advance.