Because furniture aren't settled, you may be injured when the big earthquake occurs.
Besides, it makes not only furnitures stumbling down but also dishes falling from a cupboard and injuring some people.
The reason why furniture are stumbled easily:
・It's heavy or its center of gravity is high.
・It's on the upper floor like apartments.
・It's put on tatami or floor covered by the carpet directly.
・It doesn't touch the wall.
In other word, people who live in a high place is more danger if they don't fix furniture hardly.