Sydnie Kohara:
Japanese are ever mindful of the next earthquake on the horizon, and they’re now tracking the country’s seismic activity through a mobile app. It’s called Yurekuru Call. Here’s our Tokyo contributor Rebecca Milner.

Rebecca Milner:
2011 was a big year for the smartphones in Japan. They really came into their own after the March 11th earthquake. The mega-quake knocked out cellphone reception over large swaths of the country, including Tokyo, some 230 miles away from the epicenter. The only people who could communicate were those with smartphones and access to wireless networks.

Not surprisingly, communication apps were the top free downloads in 2011. That’s according to the iTunes App Store 2011 Roundup.

The coolest free download was also linked to the March disaster. It’s called Yurekuru Call. Yure means shake, and kuru means to come. It’s an application that gives notice of earthquakes. It was created by a Japanese software developer, RC Solutions, and uses the Earthquake Early Warning System. That’s the same system used by TV and radio broadcasters. It’s overseen by the Japan Meteorological Agency. Ideally the application sends an alert a couple of seconds before the ground starts to shake, though in reality it is far from perfect.

Yurekuru existed before March 11th. However, according to its developer, downloads increased 10-fold following the quake.

Writes one tweeter, Tomoko Adachi, just a few days shy of the new year:
"This year in Japan, disaster-related apps like Yurekuru top the list."

For those whose lives were largely unaffected by the quake in northeastern Japan, Yurekuru served as a constant reminder of the country's seismic activity. It would ring in the middle of the night, it would ring in the middle of dinner, it would ring in the middle of parties, causing a momentary pause and a rush of fear.

So much did Yurekuru enter the zeitgeist for 2011, that one New Year's well-wisher by the name of Sanshiro99 tweeted, "May your Yurekuru not ring so much this year."

Sydnie Kohara:
So Rebecca, tell me exactly how this app works.

Rebecca Milner:
So here’s the app. Its symbol is a catfish, because catfish are traditionally thought to be what causes the earthquakes living underground in Japan. And when you open it up, you can see a list of all the earthquakes that have happened in Japan in the last 24 hours, where their epicenter was, and their magnitude. Now the Yurekuru app came with a default setting of magnitude two, which meant that it sent alerts to your phone every time there was an earthquake of magnitude two or over. Now following the March 11th earthquake, when aftershocks were happening literally every five minutes, that meant your phone was buzzing literally every five minutes with a notification of an earthquake, which was pretty harrowing. So after about a week, most people had agreed to set their default setting to around four, which meant that you might only get an alert every day or so.

Sydnie Kohara:
Thanks Rebecca. Rebecca Milner is LinkAsia’s Tokyo contributor.