Discussion with colleagues brought to mind the existence of the Tatsuda fault, which I’d thought to bring to your attention in the off chance that you’re getting too much rest.
Tatsudayama, as anyone who as ever hiked it knows, is a large mound of clay; gravel must be poured on its paths lest hikers slip all the way back down. (Friendly advice: don’t stray off the gravel, particularly on wet days!) The cause of its composition is that it was once riverbed that was thrust to its current height by its eponymous fault, which runs east of Mt. Kimpo and west (to the far side) of Tatsudayama. A look at the shape of the mountain shows the west side to be a straight line accompanied by a depression with river and springs.
I’d then Googled it, and the best site I could find was that from a real estate company, of course. First, for nostalgic and/or entertainment sake, note that the site had put the probability of a M7.2 - 7.6 on the Futagawa/Hinagu fault over the next 30 years at 0-6%. Ha ha! - well, seismic analyses is hard, but they were accurate on the intensity map. Okay, “been there, done that” - let’s move on.
The second map on the page shows an estimated shindo range in the event of a possible M6.5 on the Tatsuda fault, of which the chances are unknown (but, given the above prediction, would be as unreliable even if predicted).
Anyway, no need for worry! Geologic time and human time work on vastly different clocks, and the Tatsuda fault may rupture now or never (meaning after we’re all gone). The geology is quite interesting, though. - William
