Japan has a very unfortunate history with earthquakes, particularly because the country lies on a major fault line. Nevertheless, the Japanese have found several ways to counter the destructive forces of nature, and here’s a video shot at the time of the catastrophic 2011 Japan earthquake proving their superior engineering and construction mastery.
Usually, buildings fall during an earthquake as they are incapable of withstanding large seismic loading. But the building in the video shows a floor designed such that it acts as an isolated system and doesn’t crack or even move when the earthquake strikes since it can detach itself from the shaking walls and doesn’t displace with the structure.
Large displacements in stiff objects can produce large strains, and when these strains act on the connections of a building such as the connection of floor with the wall forming a 90-degree angle, it could initiate a crack very easily. These cracks are then propagated along the structure creating fault lines, leading to structural collapse. But by detaching the wall from the floor, the stress concentration point is taken out of the question, and the building remains intact.
You can even see people walking and running around without any difficulty, which is impossible during an earthquake of this magnitude. Contrary to how it seems in the video, it is actually the camera that is shaking due to being attached to the wall, and the floor is fixed at its place.
