Spoon & Tamago - japanese art, design and culture

Editor’s Note: in the days since this article was written, numerous earthquakes and aftershocks have struck, causing additional damage to the castle, and Kyushu as a whole. Earthquake resistant architecture obviously isn’t as simple as ceramic roof tiles being shaken to the ground. This article should be construed as highlighting an ancient method that architects tested in an earthquake-prone nation, rather than an modern usage of earthquake-resistant technology.

A powerful earthquake (M 6.5) rocked southern Japan on Thursday, with an even larger tremor (M 7.3) hitting on Friday. As of now the death toll is in the single digits with roughly 1000 reported injuries. Those numbers will likely rise but as of now it seems that the fluid situation could have been a lot worse. One of the more visually shocking images is the damaged Kumamoto-jo, a majestic castle dating back to 1467 and is a powerful symbol of  the Kumamoto region.

photo by Haruki Morishita / Asahi

The primary damages appears to be of the stone walls and tile roofing, which were dislodged and collapsed. The tile roofing, in particular, slide off the roof and fell to the ground, causing large plumes of smoke to rise and cause alarm. However, according to some, this was an entirely intentional mechanism of ancient Japanese architecture designed to protect structures from collapsing during earthquakes.

Japan is a country that is susceptible to both powerful hurricanes, as well as earthquakes. The heavy tile roofing, known as kawara, were designed to help structures withstand strong winds from hurricanes by weighing down the house. Their weight also provided support against small tremors.

photo by twitter user @miniminiyumiko

However, in a powerful earthquake these massively heavy roofs could overwhelm the weakened frames, causing structures to collapse. But as one twitter user says (citing their father as an architect and expert), kawara tiles were actually designed to slide off a roof during a powerful earthquake, immediately lightening the structure. It’s for this purpose that clay was used to hold the tiles in place, rather than something more permanent. However, in more modern times falling tiles were perceived as a danger and thus laid more permanently, which caused many homes to collapse during the 1995 Kobe earthquake.

Perhaps Kumamoto Castle has ancient wisdom to thank for still standing. And of course it’s concrete reconstruction added in 1960 😉