2308: Mount St. Helens

Explain xkcd: It's 'cause you're dumb.
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Mount St. Helens
It's a good mountain but it really peaked in the 80s.
Title text: It's a good mountain but it really peaked in the 80s.


This comic marks the 40 year anniversary of the May 18, 1980 eruption of Mount St. Helens that killed 57 people. It was a Monday so a normal release day could be used to mark this event.

It shows a graph of the height of the mountains in the state of Washington as a function of time over the last 100 years. The only mountain to change its height significantly over this time period is Mount St. Helens, which the comic is named after. It is also the only black line as all other (30?) lines are gray.

Mount St. Helens is a volcano that famously and explosively erupted in 1980. Millions of tons of earth were blasted from one face of the mountain all over the surrounding countryside. After it was over, the peak of Mount St. Helens was no longer the 5th highest in the state of Washington, having lost approximately 1,300 feet (400 m) in height (from 9,677 ft (2,950 m) pre-explosion to 8,363 ft (2,549 m) post-explosion).

The comic shows a rare event that had major effect and was predictable in hindsight, but would have surprised an observer that is just tracking the height of Mt. St. Helens in a non-representative timeframe. Such an event is called a Gray Rhino event.

Currently, the 5 highest mountain peaks in Washington State are Mount Rainier (at 14,411 ft or 4,392 m), Mount Adams, Mount Baker, Glacier Peak, and Bonanza Peak. As shown in the comic, Mount St. Helens was the 5th highest, but now has fallen to #35 (using a topographic prominence cut-off of 500 m (1640 feet)). Only mountains above 8,000 feet (2,438 m) are included, with the graph topping at 15,000 feet (4,572 m), 600 feet (182 m) above the highest mountain. There are 92 peaks above 8000 feet in the state, so not all are included and the lines are not really distinct below 9000 feet. Seems like there are less than 30 lines drawn. Of course it says Mountains not Mountain peaks, but there are only four mountain ranges in Washington with peaks above 8000, so he must mean peaks!

Technically, the other mountains may be fluctuating in height as well, due to erosion or the movement of Earth's tectonic plates, but this phenomenon should not be visible on the time-scale and vertical resolution that Randall has plotted. Precision GPS measurements of various peaks in Washington have only been available since 2010, and it's likely that the primarily volcanic mountains of Washington experience significant but comparatively slight variations throughout the year due to snowfall, melt, or the pressure of swelling magma inside volcanic cores. These changes go largely unmeasured, while the mountains continue to appear equally physically unchanging and imposing both in person and from a distance. Source: Seattle Times. So while the comic does appear to show some slight fluctuations in height for mountains, that is more likely a side-effect of the comic's free-hand drawing style than an accurate reflection of any real fluctuations.

The title text is a play on the term "peak" meaning both the highest point of a mountain and also the optimal, most famous or most impressive stage of a trend; for instance: "The band Rolling Stones really peaked in the 80s."


[Caption above graph:]
Heights of mountains in Washington State
Over time
[A graph is shown with close to 30 horizontal gray lines which seem not to change much, if any, as they go from left to right. Only the top 6 gray lines are distinctly separated from others. The top line is way above the second line which again is far above the next two that are close together. Two more close together is somewhat further down, and just below them the rest of the lines follow in close proximity down to the bottom of the graph. A single black line is also shown. It begins as the fifth highest line, just above the two last mentioned above. It, like all other lines, goes horizontally, but only three fifths of the way across the graph – then it immediately drops down well below most of the other lines (at 1980) and levels off, continuing on its horizontal path. There is a caption above the graph, and both Y-axis and X-axis has labels. For the Y-axis there is a tick for every label, for the X-axis only every 2nd tick has a label. A unit is given on the top label on the Y-axis.]
1920 1940 1960 1980 2000 2020

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I'm just excited that he mentioned my home state 16:20, 19 May 2020 (UTC)

I suspect the wiggles in all the hand-drawn lines are actually more than the changes in height of the various mountains, and almost certainly not correlated to the actual changes in height, since this is all unknown. Barmar (talk) 00:56, 19 May 2020 (UTC)

This comic needs to be translated to non-retard units 07:41, 19 May 2020 (UTC) <-- don't use "retard." That's really gay. Cellocgw (talk) 11:42, 20 May 2020 (UTC)

We can't expect everyone to be scientifically literate enough to understand measuring things with the planck length, superior though it may be. Besides, these are American mountains, so they're measured in American units. 16:20, 19 May 2020 (UTC)
It's pretty common to measure things in years. And while measuring in 20 year gaps isn't normal, I wouldn't call it retarded, especially when they're probably chosen for a good visual spacing. Mikemk (talk) 08:54, 19 May 2020 (UTC)
Maybe he meant feet, which is not a SI unit. I guess the user got the wrong feet out of bed this morning? ;-) --Kynde (talk) 10:04, 19 May 2020 (UTC)
All twentyish attoparsecs, you mean? (Yanks like using measures that give them bigger numbers. Feet instead of metres, inches instead of metres (or feet-and-inches), pounds instead of kilos (or stones-and-kilos), US gallons instead of UK ones, the wrong sort of billion/etc. :P ) 11:22, 19 May 2020 (UTC)
I think the graph should be labeled in seconds. I mean, gigaseconds for time and light microseconds for distance. -- Hkmaly (talk) 02:55, 20 May 2020 (UTC)
You know what? You’re mostly right (and this is coming from and American!), but I disagree with the “billion” thing. The US way makes more sense and is more common, anyway. Trogdor147 (talk) 04:26, 26 May 2023 (UTC)
I've gotten used to large figures as displayed in 'idle games' (after sufficient progression), where I can make the conversion of "15.2T" or "3.95Qi" or "657No" to pure values with the correct number of zeros if I need to.
I have to take the whole part, the fractional digits (padded up to three, with zeroes) then three times the suffix's 'number' (maybe M=1, B=2, T=3, (Qu/Qa)/Q, Qi/q (latter is case-differentiated "Q"uadrillion from "q"uintillion, where sticking to one-char suffixes), He/S, (Se/Sp)/s, Oc/O, No/N, (De/Dc)/D=10, then often aa=11, ab=12 and onwards; not sure if 20 would be "aj" as next in a lower-case lower-case base26ish progression ("az"+1="ba") or go for "b(z?)" then "ba" for 21 in "alpha-coded decimal" where "aaa" would appear at 111-illions... I've never yet had to deal with such magnitudes). Anyway, 'simple'. Ish. (Though I find that "35O" in typical fonts can look too much like "Three hundred and fifty" rather than the actual "Thirty-five Octillion", for apps that go with that particular coded convention. And "23.5O" only disambiguates easily when you realise a figure never uses fractional non-suffixed numbers and/or doesn't zero-pad to 2DP.)
Thus "15 200 000 000 000" (spaces given for convenience, or instead of the ","/"." thousand separator of choice/localisation), "3 950 000 000 000 000 000" and "657 000 000 000 000 000 000 000 000 000 000" for those initially given examples.
So there's a logic to the Short Scale, in deriving the full numbers. But as well as the initial 'whole number' (1<=n<=999) and the suffix 'magnitude padding' you always have to add three arbitrary digits that represent the (typically two or less) decimal places. A permanent off-by-three adjustment.
With the Long Scale, it'd just be straight 6xSuffix digits (the first few being any decimals, then zero-padded). With perhaps something like "Xd" for "X-illiard"s (or "tX" for "thousand X-illion" under traditional British expansion) of this 6x and the directly implied extra 3, or just go for "#####0(.##?)X" format, but the adjustment is at least justified. And you run out of any given run of clearly understandable suffixes at roughly double the magnitude of the point at which ran out of them in the Short version.
So, while I wouldn't wish to change the 'standard', I think it's clearly not the more logical or descriptive one.
Also note that (excluding the huge 'other scale' populations which actually includes the top two most populous nations) it is clear that Long Scale is not exactly rare. For example plenty of 'old world' countries with reasonably packed populations, compared with a number of large Short Scale/Short-with-Milliard territories with low densities across most of their sprawling areas (e.g. US, Russia, Brazil, Australia, trans-Sahara nations...). There's the mixed-use ones as well. Canada is steadfastly Anglo-French hybrid in various ways, of course they're not melded to either system, in one of the largest countries by area (actual or by distorted map area) if you don't like reducing to populations. And in the whole of (most distorted) Antarctica probably most of its few multinational 'inhabitants' instead prefer to resort to SI prefixes and/or powers-of-ten anyway!
So "makes more sense"[actual citation needed] and "more common"[actual citation needed] are dubious by almost any definition... IMO! 09:37, 26 May 2023 (UTC)
Fair enough! I feel like I've seen the short scale more in professional contexts, but that could just be me. And you're completely right that saying either scale "makes more sense" is dubious. I was most certainly a fool... last year. Trogdor147 (talk) 04:27, 14 May 2024 (UTC)
Wow you're so cool and epic for using slurs good job
1. That was unnecessary. 2. I honestly don’t care what units people use, as long they aren’t super obscure (like furlongs or smoots). 3. Yes, I know this discussion is 3 years old, and I don’t care (also I’m new here and I want to be a part of things). Trogdor147 (talk) 04:20, 26 May 2023 (UTC)

Could be linked to sudden changes to covid-19 charts due to lockdowns 12:12, 19 May 2020 (UTC)

It might have been inspired by the art installation where someone cut off the peak (one inch of rock) of Scafell Pike.

According to the wikipedia article, "The eruption ejected more than one cubic mile (4.2 km^3) of material." That's going to be billions of tonnes, rather than the thousands mentioned in the explanation. 15:23, 19 May 2020 (UTC) I don't think I'm going to be able to contribute here any more if I keep having to provide free training for Google's image recognition of weird American street scenes. What's a "crosswalk" and what does it look like anyway?

A "crosswalk" is a "pedestrian crossing" in other types of English). 16:46, 19 May 2020 (UTC)

I suspect the true slope of the line during that transition period is a heck of a lot closer to negative infinity than as drawn. #itsajokedammit Cellocgw (talk) 11:44, 20 May 2020 (UTC)