Most homes will have all furniture and shelves secured to walls and the floor to prevent them from falling over in larger tremors.
In the event of a large earthquake that causes a tsunami, Japan has one of the leading tsunami warning systems that can broadcast alerts across the nation if there are expected waves. In the case of the 2011 earthquake and tsunami, this gave some residents nearly 10 minutes advance warning, though in many cases it wasn’t enough. The system was upgraded shortly after 2011 to provide more substantial alerts and give residents more time to get to shelter. In the case of smaller tsunamis, most piers will have concrete blocks in the shape of stars that help defuse wave size and speed. I’m currently aware of alerts through text, email, radio, loud speakers in town and television.
