Earthquakes, as you may have noticed, are not uncommon in Japan. We had a rather big one late on Wednesday night. This link to NHK News shows what happened as it happened - what look like explosions are in fact power outages from electricity sub-stations.
It woke me (though my Japanese wife and reared-in-Japan son slept right through it. Centuries of geological-genetic conditioning perhaps? Could be a research paper in it.)
Anyway, the foreigner was woken. Now interestingly, I woke about a minute or so before the house began to shake. And even in my liminal state (with Sanae's snoring the only disturbance), I knew there was a tremor coming.
Earthquakes are essentially waves of energy dissipated from the source of the quake. And there are three types of wave: surface waves, p-waves ('p' for 'primary' or 'pressure'), and s-waves ('s' for 'secondary' or 'sheer'). S-waves are the ones that cause the seismic tremors resulting in damage. P-waves are considerably less intense and arrive before the s-waves as they travel through the earth considerably faster. Earthquake warning sensors are designed to detect these p-waves and provide advance warning of the stronger s-waves that cause all the shaking, rattling and rolling.
Here is a diagram I uploaded from the internet expertly designed to explain waves.
.PNG)
Many animals can sense these p-waves (it is often why you see birds suddenly take flight before an earthquake strikes), as can some humans.
I am one of those humans. Apparently I am possessed of 'keen senses' (whereas Cian is often possessed of no sense at all) that can 'feel' the vibrations made by a p-wave. Which, here in Japan, makes me akin to a minor deity. Or a demon. I am not too sure which.
Anyway, not for the first time, I awoke in the middle of night knowing that there was an earthquake imminent. And I have no idea, coming from a seismically inert country like Ireland, how I ever developed such a sense.
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