If one of those tectonic plates gets a bit uppity and starts to slide on top of another tectonic plate, or if the pressure of the three of them pushing against each other causes them to slip, jar or judder, you have yourselves an earthquake. Tokyo experiences dozens of earthquakes a day. Some so small you don't feel them. Others so big they rock your world. But not in a good way.
Let me just state quite clearly for the record that living with earthquakes is weird. It's odd. And depending on how much those bolshy tectonic plates judder, it may or may not cause you to feel the need to change your big-girl pants.
I experienced my first tangible earthquake during my second week of teaching in Japan. I was sat around a small circular table with three students, going through the basics. This is a pen. That is a book. This is a pencil. That... is a whole lot of rocking going on... is anybody else feeling this... whoa there Neddy... am I drunk... don't panic... everything is fine... it hasn't stopped yet... it's getting worse... why are my students getting under the table... no, I'm not getting under there with you... oh, ok, but don't... Good Gordon, the sky is falling in... move over, move over.
Is there a polite way to sit under a table with people you've only just met? No.
When we resurfaced, my students were delighted to have shared my first earthquake experience. They weren't the slightest bit shaken or stirred. I was, erm, what's the technical term? Oh, yes, freaking out.
That was an earthquake? An earthquake? AN EARTHQUAKE. So much swaying. Can I be excused? I feel a tad sick.
You start to evaluate your environment differently when you live in a world that really does rock. Bookshelves are fixed to the wall, so that you don't suddenly find yourself reading all your books at once. Precious items are displayed on lower down shelves. You don't tend to have a lot of clutter that can jiggle its way to being broken. You don't sleep next to anything heavy that can be thrown or dislodged and land on top of you.
A friend of mine from New Zealand took to sleeping with his motorbike helmet next to the bed in case of earthquakes. If the earth started to move, and he wasn't responsible, he would leap out of bed and cram on the helmet. He felt that if the house fell in at least his head would still be in one piece. Until his wife pointed out that a motorbike helmet untethered in a room during a big earthquake would probably be the thing to do him in. Particularly in the case of The Big One.
The Big One.
Ask any person living in Japan about The Big One and they will have lots to tell you. The Big One last hit Tokyo in 1923. 1st September 1923 at 11.58am to be precise. Lunch time. The time when most households were cooking lunch on open flames. The close proximity of the houses and the fact that they were mainly constructed with wood meant that most people killed as a result of the Great Kanto Earthquake of 1923 died in the fires that raged for two days after the earthquake rather than as a result of the earthquake itself. The earthquake measured 8.3 on the Richter scale and moved the 93 tonne Buddha statue in Kamakura two feet forwards on its stone base. Approximately 140,000 people died. Scary stuff.
My Japanese students and friends took great delight in telling me these facts repeatedly during my time in Japan. I had to change my big-girl pants a lot.
According to my Japanese friends, seismoligists had studied the frequency of strong earthquakes taking place in the Kanto region where I lived, and had found that there was a pattern. The Big One hit the Kanto region around Tokyo roughly every 70 years. The last one had hit in 1923. I arrived in Tokyo, flushed with the excitement and anticipation of the adventures ahead in 1993. You do the maths.
You can imagine my dismay.
Twenty two months after I arrived in Tokyo The Big One hit. Only it didn't hit Tokyo. To everyone's surprise it hit the Kansai region of Japan hundreds of miles to the south of Tokyo.
At 5.46am on Tuesday January 17th 1995 in the southern part of Hyogo prefecture 20km from Kobe, the Great Hanshin Earthquake hit. I was in bed asleep and was woken up by a gentle quaking. I thought it was another small earthquake in the Tokyo area. When I turned on the tv, in the morning as I got ready for work, I saw orange ticker tape running across the screen giving emergency information, and scenes of fires raging amid collapsed buildings. Six thousand four hundred and thirty four people died, including teachers I had met who worked for the same company as I did in the Kansai region, and students I had taught who had had the misfortune to travel home to visit families that week. Three hundred thousand were left homeless. For days my room mate and I followed the news watching the drama unfold. Very sad and scary stuff.
It was at this point that my Japanese friends decided that now was a good time to tell me about the rumours they had heard that the Kansai earthquake was actually the precursor to The Kanto Big One that was due to arrive any time soon. So I should go to the supermarket and put together my survival kit. They weren't joking.
Here is a list of the items my friends and the local government were advising me to gather together.
Bottled water/enough for 6 days.
Tins of tuna/enough tinned foodstuffs to last 6 days
A basic first aid kit
A battery powered radio
Any medications you usually take on a daily basis, one month's supply.
Again, there was some changing of big-girl pants. And some mild concern at how I was going to carry 12 litres of water and more tinned fish than you could waggle a stick at whilst climbing out of a wobbling window.
For several months after the Great Hanshin Earthquake, Tokyo was on high alert. Seismologists couldn't understand how they had got it so wrong. The Kansai area where the Hanshin earthquake struck was considered a "safe zone" in Japan as it had experienced far fewer earthquakes than the Kanto area around Tokyo, and, unlike Tokyo, was not directly over the meeting point of the three tectonic plates.
In supermarkets in and around Tokyo, displays were set up showing the items that your personal survivial kit should contain. Nicely emphasised with huge cardboard flames that licked their way around the displayed items. And a supermarket employee in quasi-police uniform shouting at you with a mega phone to "BUY YOUR SURVIVAL KIT HERE!" I kid you not. Seriously. Every time I needed a packet of tofu and whipped into my local store, I would see these horrifying displays and come out hyperventilating.
I put together my survival kit. It was so heavy and unwieldy that if a big earthquake had hit, I'd have been put out of my misery by my survival kit-bag as it was thrown around the room.
I searched around the area near my flat and found a lovely new place to rent called Casa Hawaii. A shared house with people from various countries who had come to live and work in the Tokyo metropolis. I paid my rent, signed the contract and moved in.
But that's another story.