Numbers alone can be hard to visualize, but this makes things terrifyingly easy to understand.

How tall is a wave?

If you’re an avid surfer or sailor, you’ve probably got a pretty solid image of the height of a typical wave. But if your personal or professional interests lie outside those fields, odds are your grasp of the concept is a little less distinct, especially if asked to put it in numeric terms.

Still, most of us know that 16.7 meters (54.8 feet) is a really big wave. But…just how big?

I didn’t pick that number out of thin air, by the way. According to Yahoo! Japan, that’s the highest observed height of the March 11, 2011 tsunami in Iwate’s Prefecture’s Ofunato City. Roughly 3,500 homes, more than a fifth of all residences in the city, were destroyed in the tsunami, which also claimed the lives of more than 300 of its citizens.

So again, just how high is a 16.7-meter wave? As high as the red line on this skyscraper.

That’s the Sony Building in downtown Tokyo’s Ginza district, where until March 12, Yahoo! Japan will be displaying the following message.

Every year, when 3-11 comes, we look back on what happened on that day. Six years have already passed since the Great East Japan Earthquake. We tell ourselves that disasters won’t happen again. But someday, a another disaster will probably, no, definitely occur.

On 3-11, in Iwate Prefecture’s Ofunato City, the maximum height at which the tsunami was observed was 16.7 meters. If the tsunami had happened here, in the middle of Ginza, it would be exactly this [the red section’s] height.

It’s higher than one would imagine. But just by knowing how high it is, the actions we take can change. We can make preparations here and now. We can receive the understanding and knowledge through our memories of the victims.

We won’t forget what happened that day. Yahoo believes that this is the most important part of disaster preparedness.

Making things even more chilling is that while Yahoo! Japan lists the tsunami’s height at 16.7 meters, Japan’s Kyodo News reportedly estimated the wave reached a height of 23.6 meters in Ofunato, which would move the mark even closer to the top of the 31-meter Sony Building.

Yahoo! Japan’s message makes no mention of or appeal to its services, and instead serves strictly as a somber reminder of how fragile life can be, and of the importance of being prepared for the worst even as we appreciate the times when circumstances allow us to enjoy the best.

Source: IT Media, Kyodo News via Wayback Machine, NPR, Twitter/@sho_lab