Mapping Doomsday

Published 12 years, 7 months ago

This past Friday night, in conversation with a couple of our friends, the subject of high school fears of annihilation came up.  Ferrett said he’d done a class project showing how, if New York City got hit with a nuclear warhead, his home town of Norwalk, CT would be destroyed as well.

“Wait a minute, that can’t be right,” I said.  “How far is it from Manhattan to Norwalk?”

He didn’t know for sure, so we went to Google Maps for a rough estimate.  49.2 miles, it said, although of course that’s a driving distance, not a straight-line measure.

Still, I felt confident in asserting that no way would Norwalk be destroyed.  Not even with a 20-megaton warhead, which was what he remembered using in his example.  A few windows might get shattered, and of course if the wind were from the southwest they’d be getting a whole lot of fallout.  But flattened?  No.  I was pretty sure not.

“Hold on,” I said, “I’ll be right back.”

I ran up to the library and went straight to the “military and arms control” shelf, where I pulled out my copy of “The Effects of Nuclear Weapons”, 3rd Edition (1977).  In the back, it has this handy “Nuclear Bomb Effects Computer”, a circular slide-rule type of affair.  You can fiddle with an online version of the calculator from the 2nd Edition (1962) of the same book, and the complete text of the 3rd Edition is also available online.  I went back downstairs and pulled out the calculator.

Humming to myself, I slipped and swished the dials until I came up with the answer a bit more severe than expected, but not terribly far off.  At a range of 45 miles, the maximum overpressure for an optimum-altitude air burst with a 20MT yield would be somewhere around 0.8psi.  The calculator actually doesn’t show overpressure figures below 1psi for optimum-altitude bursts, though it goes down to 0.1psi for ground bursts.  It also doesn’t go any higher than a 20MT yield.  A 0.8psi overpressure would shatter most windows, particularly those facing the shock wave, and might cause light damage to some residential homes.  The direct thermal radiation, even assuming line-of-sight to the fireball, would be less than 1 cal/cm2, which isn’t enough to cause any damage.  Otherwise, there would be a brief pulse of 30-mile-per-hour wind as the shock wave passed, and of course there would be EMP effects.  And, you know, fallout.

So it’s not like things would be all peaches and cream for the folks in Norwalk, but the town would still be standing.

At this point, I wondered if there were perhaps a tool online that would show this sort of information more visually.  I Googled a bit more, and came up with the Nuclear Weapon Effects Calculator, which lets you pick from a short list of cities, dial up the yield of your explosion, and click on the image to change the detonation point.  Guess where they got their data for the thermal ring, as well as the 5psi and 2psi thresholds?  Yep: “The Effects of Nuclear Weapons”, 3rd Edition.

That’s when my inner geek kicked into overdrive.  I’d been meaning to dig into the Google Maps API anyway, so I signed up for a key and developed my own version.  I call it HYDESim, which stands for “High-Yield Detonation Effects Simulator”.  You can pick from a list of cities or input any latitude/longitude coordinates Google Maps covers, set the yield you find most interesting, and see what the effects might be.  Each successive ring marks a successive overpressure threshold: 15psi, 5psi, 2psi, 1psi.  I included 0.25psi in the list because it’s the point at which even windows wouldn’t be damaged, but left it off the map because it was too huge.  (I thought about adding a way to switch psi rings on and off, and in the end didn’t feel like doing the necessary hackery.)  15psi is the point at which reinforced-concrete structures might be able to survive with severe damage; 5psi is where homes might start to survive with severe damage; and 2psi is where home damage drops to light.  Roughly speaking.

I didn’t include rings for thermal effects or electromagnetic pulses: this is strictly about blast wave damage.  It’s also “idealized”, which means that there’s no effort made to account for terrain changes, urban density, ground type, and so on.  The script just uses the formulae and information in the book to calculate maximum-overpressure distances for arbitrary yields, and plops down circles as appropriate.  So the “Simulator” part of the name is probably exceedingly grandiose.  Then again, you never know what a future spate of hacking might bring.

Also: apologies to New Yorkers that your city is the default target, but its destruction and the follow-on physical effects in Norwalk are what got me started on this… and, let’s face it, in any wide-scale nuclear conflict, you’d have been the top city on the target list.

Doing this was an interesting exercise in both Google Maps programming and lightweight AJAX, which I’d also been meaning to investigate; the city list is built from an XML file that sits outside the XHTML document and its scripts.  I’ll have some observations about the Google Maps API in another post— specifically, what I found to be major limitations given what I was trying to do— but for now, here’s your chance to get a slightly more concrete idea of what had us all so scared during the Cold War.  As the simulator demonstrates, even a 1MT (1000KT) device could do a whole lot of damage.

  1. Coincidentally, I was reading about something related to this just a few days ago. From the map it looks like 50 megatons would’ve been more than enough to level most of the place I grew up in. Scary thought.

  2. Error message:

    The Google Maps API key used on this web site was registered for a different web site. You can generate a new key for this web site at

  3. FYI: The lethality at an overpressure of one atmosphere (14 PSI) is under one percent. So, with relationship to people getting hurt by the blast itself, only the inner most red circle is of any importance.

  4. #3: That’s only one part of it though, basically a nuclear explosion does several things at once:
    1. Pressure wave that damages buildings
    2. EMP which fries any (unshielded) electronics in the affected area
    3. X-Rays or whatever that cause the radioactive fallout afterwards
    4. A bunch of other radiation across the rest of the electromagnetic spectrum

    Number 4 is actually most dangerous to people in the short term since it includes infrared light – basically if there’s a line of sight between you and the explosion you’ll get cooked, which is why those old WW2 films tell people to get inside a building, cover themselves etc.

  5. How long has it taken to develop this Google Maps hack?

  6. Kris: The Google Maps API key error message will be triggered if the URL to which I linked is altered in any way whatsover– including change the hostname from ‘’ to ‘’. That’s the only thing I can imagine would be causing the error, since it works fine for me. This is one of the things I find annoying about the Google Maps API, but that’s a post for another time.

    Julian: probably ten hours or less. Factor in this being my first-ever exposure to the API and to AJAX coding, needing help figuring out some of the JavaScript, and having to work out the math needed to drive the various and subdry calculations; and you can see how easy it is to develop new tools. Not that HYDESim is perfect– it has some flaws, and the Maps API itself is only partially to blame. But still, I was able to turn it around pretty darned fast.

  7. Racer: as Ant points out, the importance of the pressure wave isn’t what it can do to a human directly, but what it does to the environment that can hurt a human. 14psi might well collapse most apartment buildings, for example, which would be deeply harmful to its occupants. 7psi will do severe damage to most homes. Even at 0.25psi – 1psi, glass will shatter, and the shards could easily be injurious or deadly. So it’s a lot more than the inner ring. And that’s just the straightforward physical effects. The fire damage caused by the thermal pulse is completely omitted, as is the other stuff Ant mentioned.

  8. Eric, in the seventh paragraph (the one about megatonnage and psi), you forgot to close an <acronym> tag. All that text can’t just stand for “megaton,” can it? :)

  9. Juxtapositions

    I may be the only person who reads both Susan Kitchens’ and Eric Meyer’s blogs. But the juxtaposition of this and this is just too creepy….

  10. Do you plan on adding SI units to this?
    Most of the world does not actually use psi and miles :-)
    Also, an option for entering degree, arcminutes and arcseconds instead of decimal degree for langitute and latitude would be cool.

  11. You understand that you are looking at the maps generated with a flawed perception.

    That red center is a hole in the ground. There is nothing around the perimeter that you can recognize. There are fires and smoke everywhere, and no one to put them out. There are no hospitals, nurses or doctors. No one can help. The head is dead.

    And that will go on for a while in the area hit. … While everyone else is trying, futiley, to seal their borders. … What? You only expect them to do this once?

  12. Sebastian: I may go over to SI, or offer it as an option. The calculator and book all use miles/psi/etc., so that’s what I used.

    Jack: Actually, the hole in the ground from a surface burst (which is what HYDESim models) is substantially smaller than the red center. For example, a 100KT surface detonation in a city, which I’ll take to be equivalent to dry soft soil/wet hard rock, would create a crater just shy of 0.045 miles in radius and just over 0.02 miles deep, with an ejecta blanket roughly one-tenth of a mile in radius.

    That’s ejecta from the ground, not rubble from the surroundings. The red center is indeed the zone in which basically everything will be rubble, although there will likely be very few fires there due to the shock wave effects. The fires will be in a ring around the center—the depth of the ring being related to the yield, of course. The fire might spread back into the central rubble eventually, depending on various factors. There will also be severe to moderate damage of structures between the 15psi and 5psi rings, many of which will also collapse, and most of which will burn.

    As for the rest of your comment, the maps don’t say anything one way or the other about reconstruction or assistance, so any flaw in perception there is an effect of the viewer, not the tool. It simply presents the damage zones from blast effects (and may one day include thermal and other effects). It doesn’t even try to calculate casualties or flow of supplies, since Google Maps doesn’t include things like access to population density data or political decisions in its API.

  13. Dori from Backup Brain brought this post to my attention. I’ve got a “Blogging as if it were 1945” project going on at 2020 Hindsight … specifically about the Manhattan project (liveblogging its development, timeshifted by 60 years).

    Anyway, have been reading up on all kindsa stuff bomb related. Lemme see if I can dig out a coupla scenarios I read last night, one of which involved Manhattan.

    Aaah, here it is, from the Atomic Archive > Science > Example Scenarios > Manhattan. There’s also one for San Francisco. Both discuss damages in concentric rings from the Zero point.

  14. Nice work, even if it’s causing scenes from The Day After to race through my mind again.

    Any chance of adding the ability to link to a particular location? You could potentially do this by allowing the “lon” and “lan” values of “id” to be added via a query string in the URL.

  15. Quite a morbid tool Eric. Banging -0.12, 51.515 into the Lati/Longditude even more so.

  16. The thing that always bothered me, living about 45 miles from Omaha and the big underground command center there, was the accuracy of whatever delivery vehicle was used for such an hypothetical attack.

    Suppose the flight path from Boris Badinov to Target (the objective, not the department store, though the store is probably a reasonable objective) is 100% as planned. Then they would hit the city center and all of the numbers would be good. Broken windows in Norwalk and Lincoln. But what if their missile guidance is only as good as their ballpoint pens?

    Might they then aim for Omaha and hit… Minneapolis? Aim for NewYork and hit… Boston?

  17. So what does this look like for a suitcase nuke (along with “bunker busters,” arguably the most likely nuke to actually be detonated in the near term. That would be a surface (or underground) blast and probably much smaller than a missile. Also, aren’t most modern missiles MIRVs? So a blast in New York wouldn’t be isolated, but accompanied by many nearby blasts (and intersecting shock waves).

    Not a pretty picture.

  18. Susan: I found you through Dori as well. Nice stuff! In my Googling around for a tool like the one I ended up building, I’d found the same page to which you linked. I went back and compared their 5psi and 2psi rings to mine, and found they were fairly close, which made me feel better about my math. I think they pushed the 2psi ring out further, but it’s hard to tell if they drew their rings at the exact psi thresholds and rounded to the nearest second, or they calculated the placement of the shock wave at each second and rounded to the nearest psi.

    Craig: since you asked, it’s there now. Thanks for the request– it pushed me to learn a little but more about JS and the handling of URL parameters.

    Dethe: HYDESim’s data is all based on a ground-level explosion. I may some day add an option for switching between ground-level and optimum burst altitude explosions. It’s true that the picture presented by the tool is unrealistic for a strategic nuclear war, which would involve several weapons being dropped in and around New York City. Managing multiple detonations proved to be too clumsy, so I stuck to just one. (Though the code should be able to support more than that.)

  19. Regarding the characteristics of a “suitcase” nuke, a RAND publication from 2003, Individual Preparedness and Response to Chemical, Radiological, Nuclear, and Biological Terrorist Attacks, states:

    While it is not possible to predict the characteristics of future terrorist attacks, they are probably more likely to use a single smaller weapon that ranges from less than a
    kiloton to 10 kilotons and are likely to detonate the nuclear device on the
    ground, not in the air.

  20. Thanks Eric, works great — and adding the yield was a clever addition.

  21. I’m tempted to forward this on to people I know who actually do these types of calculations for a living, but I fear you wouldn’t want to hear from them. :-)

  22. Wow, nice work Eric. I guess the authorities will come knocking soon enough ;P.

    I have a 2nd edition of that book from high school in the mid-80s. Nice to know there is someone else out there with an interesting interest ;)

    Oh, for all who care. I’ve been to both Nagasaki and Hiroshima and I can tell you, it all sucks. I wouldn’t wish an overdose of hospital x-rays let alone a nuke on anyone. And the large format pics at Hiroshima, wow. Oh and the “shadows” burned into stone at ground zero, eerie.

    Enough said. Nice work on the tool.

    Oh did I mention the authorities are coming, hehe.

  23. Is it assumed that only US cities are susceptible to attacks? [sarcasm] The drop-down menu suggests so.

    You have proven to me that you can very proficiently code the code as well as talk the talk. Excellent work.

  24. Sweet. I’m particularly enjoying the incongruously boyish enthusiasm over cataclysmic nuclear scenarios :)

  25. “that’s wack yo” sums up my opinion quite nicely.

    Anyone know the Redmond street address? ;-)

    Better watch out, Eric, you might be labelled a terrorist for giving people a tool to see how much destruction you can do with a nuke. :-|


  26. Eric Meyer’s HYDESim

    Eric Meyer’s put together “HYDESim“, a program designed to show you what would happen if you dropped a nuke on a certain place.
    If you need your lat/long coordinates, check out Wikipedia for your town [or the location nearest to you…

  27. “Still, I felt confident in asserting that no way would Norwalk be destroyed. Not even with a 20-megaton warhead, which was what he remembered using in his example. A few windows might get shattered, and of course if the wind were from the southwest they”d be getting a whole lot of fallout”

    Actually, if you are close enough to a nuclear explosion to have the windows even rattle, you will be killed very quickly by the radiation, making the “hide under the desk from broken glass” drill pointless. If it SHATTERED glass? Well, you’d better head to church.

  28. The Halifax Explosion shattered glass in Truro, 100km away, even though it was only approximately 2kt

  29. “Dad, Noah’s having fun blowing up the world…”

  30. […] aimed, and McGonagall straightened up with a grin, just as good as new. – misia Profound Eric Meyer has written a Nuke Simulator using the Google Maps API. Cool. If anyone […]

  31. Da Bomb

    First, I want to recommend to you Susan Kitchen’s excellent series of posts on the events surrounding the first three atomic bomb explosions (Trinity, Hiroshima, and Nagasaki). She’s blogging like it was 1945, which really brings history to life. I

  32. I’ve been curious about calculating the effects of nuclear strikes on the refineries in the SF Bay Area for a while. Like your friend this has a basis in high school during the 80’s. In my case its a role playing game called Twilight 2000.

    Anyway, I stumbled on your calculator last night and it is almost exactly what I was looking for or trying to accomplish. Just wanted to give you some props and say that your work is pretty cool. Even if it is a bit depressing to calculate the destruction of your home. :-)

  33. […] strangely fascinating. How safe is your house from Nuclear attack. London is ‘ -0.13, 51.5 ‘. And that’s ‘Nu-clear’ for any Americans, […]

  34. looks like somebody was “inspired” by this recently: ground zero maplet

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