Volatility terrain

Every ridgeline is one instrument, and runs left to right across the days most of the market traded, oldest first. Its height on a day is that day's move measured in the instrument's own standard deviations: the close-to-close return divided by the volatility of its previous 20 daily returns. That puts a currency, a coin and a stock on one scale, so a ridge reads the same wherever it rises. Moves beyond 2.5σ are tinted green when the instrument rose and red when it fell, and the quake log carries each one's signed move. The ridgelines are grouped by asset class, and the page draws the majors plus the instruments with the biggest days; the quake log covers every instrument.

A ridge running across many lines on the same day is the board moving as one, usually one macro driver rather than many stories. A gap in a line is a day that instrument did not trade, and is never drawn as calm ground. Weekends, when only crypto trades, are left off the landscape; crypto's weekend sessions are still in the log.

The gold step at the right-hand end is now: each market's move over the last 24 hours in the same σ, for the markets trading at this moment. It is not a closed day, and its numerator is a trailing 24 hours while its denominator is close-to-close over whole days, so mid-session it reads slightly tame. A live quake banner appears only when a major market is at 4σ or more, any market at 5σ or more, or a broad share of the board is beyond 3σ at once.

A quake is a move of 3σ or more. If daily returns followed a normal curve, about one day in 370 would be one. They do not: markets have fat tails, and the share of quake days above is the measure of how fat. "Its largest" means the instrument's biggest move of the window, by size, either direction. The window rolls a day at a time, so a quake leaves the log once its day leaves the window; it stays on record in the quake archive, with a page of its own.

This describes what already happened. A large move is not a signal that another will follow, in either direction.