Answer：Long shaking that occurs during large earthquakes.
●Shakes tall buildings significantly for long periods of time.
●Can be transmitted far away.
●The shaking may last for more than 10 minutes.。
●Large shaking may cause furniture to fall over or fall off.
Large, long-period shaking even at distances of several hundred km from where the earthquake occurred
Even if the earthquake intensity is small at a distance from the epicenter, the shaking can be large on the upper floors of a building.
Long-period seismic motion occurs, high-rise buildings may continue to shake significantly for a long period of time.
This can cause major deformation of the building, and may cause furniture on upper floors to topple over or move so far that they collide with people.
In fact, in the 2011 off the Pacific coast of Tohoku Earthquake, high-rise buildings in Tokyo (maximum intensity 5+) suffered falling ceilings, sprinkler failures and elevator failures.
