The mega-quake advisory, Chiba, and you

What to know and how to find out

3/11, the end of my Tokyo decade

March 11th, 2011, marked my last day at a Tokyo high school. I had just secured a new contract with a municipal job in Chiba Prefecture. I was winding down my contract and was a little out of sorts that day. I’d left my bento box lunch in the fridge, an hour’s commute back. My coworkers were preoccupied with year-end affairs, so I figured I’d head home early as it was sunny, my bento box lunch was waiting, and I thought I’d get ahead of weekend chores.

I never made it back to Tokyo. That afternoon, as I was taking a break from cleaning, a slight tremor shook my apartment building. I turned off the gas ring (I’d been looking forward to a coffee break) as the shake continued and intensified. I stood bracing myself against the walls of my galley kitchen for nearly six minutes as the building deformed, crockery and art fell and shattered, and my neighbors screamed over the noise of rattling structures. It’s a bit of a blur, but I recall a roar, possibly infrasound, coming from below.

With my heart racing, I dashed off a message on social media to say I was okay and tuned into the emergency broadcast on NHK in real time to learn that the quake’s epicenter was over 300 km away off the coast of Sendai City. In moments, I understood this was a historic seismic event. Throughout the night, I kept company on messaging apps with coworkers and friends walking home for hours as train transportation was halted.

What’s it got to do with Chiba Prefecture?

Awa Kamogawa ocean view Photo by wanderplans.com on Unsplash

By now, you’ve probably been bombarded with news that the Japan Meteorological Agency issued a first-ever Nankai Trough earthquake advisory 南海トラフ地震臨時情報 (Nankai torafu jishin rinji jōhō) after last Thursday evening’s 7.1 magnitude shake originating off the coast of Kyushu. It doesn’t mean that a monster quake is guaranteed to happen, but the possibility of a major seismic disaster is higher than normal. The predicted quakes are magnitude 8 or 9. And while Kyushu is far away, Chiba Prefecture is on the monster quake’s hit list.

The anticipated shakes

In the predicted Nankai Trough event, Chiba Prefecture and other Kanto region areas are expected to reach Shindo 5 plus. The seismic intensity scale, 気象庁震度階級 (Kishouchou shindo kaikyuu) describes the level of shaking from 0 to 7. At Shindo upper 5, furniture falls over, concrete walls collapse, and people struggle to stand up.

And the tsunami risk to coastal Chiba

The shake I experienced on March 11th, 2011 was Shindo 5. The Nankai shake in Kanto won’t be fun, but we’ll get through it. But I did mention Nankai’s taking aim at Chiba. Chiba Nippo, a regional news outlet, has an overview of municipal responses to the tsunami threat. Futtsu City facing Tokyo Bay to the bottom of the Boso Peninsula to Choshi City on the Pacific coast can expect 5-11 meter high waves within 30 minutes of the tremors.

Getting information you can comprehend

There is English language information from various national and regional government bodies and media, but it’s not corralled in one place.

In the event of a seismic or other emergency, you’ll see and hear alerts on TV and radio broadcasts, your mobile device, and municipal public address systems relayed by J-Alert Jアラート(J Arāto)¹. Japan’s earthquake early warning system 緊急地震速報 (Kinkyū jishin sokuhō), sends messages to cellular phone providers, so as long as you are connected to a cellular network, you’ll get a localized heads-up.

One caveat is that though the alerts are relayed to target regions in seconds, you may feel a shake before or after the alert. Or not at all. It all depends on proximity to the seismic event. And those messages will be loaded with kanji. For those who struggle to read Japanese, there are English smartphone apps such as Nerv app with IOS and Google Play versions.

If you’re like me, weak at reading but with good listening comprehension, you can listen to NHK Radio on the web or with the smartphone app. For those still learning Japanese, I recommend bookmarking NHK World, as the national broadcaster that provides live coverage in English (and news in a dozen other languages) in an emergency. In addition, the English-language Japan Times opens a disaster portal with a live blog of news and updates in an emergency.

And if you’re in one of the 18 cities, towns, and a village at risk of tsunamis, you ought to familiarize yourself with your municipal homepage. Each government has information about evacuation plans, shelters, cooperation with corporations and institutions, and emergency broadcasts.

Get you and your household ready

I’m not trying to scare you but Japan is prone to disasters. However, it’s also resilient because of preparation, communication, and infrastructure. A lot of that comes down to the family and individual level. One of the best guides I’ve found to prepare you and your loved ones is the Tokyo Government book, Let’s Get Prepared. Much of the information is universal - how to secure your home, stockpile, pack emergency bags, and what to do wherever you may be in an emergency. Considering that many Chiba residents commute to Tokyo, it’s an indispensable guide.

Communication lifelines

One out-of-date point in that guide is the disaster message service. J-Anpi was discontinued in 2023. As part of your emergency prep, take note of other channels open in an emergency. NTT has a webpage listing message boards offered by mobile phone carriers and NTT itself. Wireless LAN, active right now as I type this², becomes available in disasters. Watch the YouTube video to see how it works - 00000Japan.

I’ll sign off in the words of Canada’s CBC evening news anchor, Tom Harrington - Stay safe, and take care of each other.

1. The Japan Meteorological Agency’s book Earthquakes and Tsunamis - Observation and Disaster Mitigation infographic shows the flow of information from seismic monitors to public services and mobile network operators, mentioning J-Alert.

2. In response to Typhoon Maria (Typhoon #5) approaching the coast of Iwate Prefecture on August 11th, Wi-Biz (Wireless LAN Business Promotion Liaison Council) opened WiFi service for Oshu City.