Public-domain source · no model output

Nuclear Bomb Map — the rings on the ground, not on a chart

The same five distances as the nuclear bomb blast radius table, drawn where they actually land. Pick a city, pick a yield, and the rings are laid over the ground at true scale, north-up. Every number behind a ring still carries the figure and printed page it came from.

New York · 100 kt · air burst

Ring centre 40.7143° N, 74.0060° W — a GeoNames gazetteer point, not an administrative centroid.

City

New York Los Angeles Chicago Houston San Francisco Washington, D.C. Miami Seattle Boston Atlanta London Paris Tokyo Berlin Sydney Toronto Mexico City São Paulo New Delhi Johannesburg

Yield

15 kt 100 kt 1,000 kt

Burst

Air Contact

The map draws with scripting. The distances it would draw for this city are listed below, and every combination is in the nuclear bomb blast radius table.

• Fireball 0.21 km Eq. (2.127.1) · p. 70
• 5 psi overpressure 3.22 km Ch. 3 · Fig. 3.73c · p. 115
• 1 psi overpressure 9.93 km Ch. 3 · Fig. 3.73c · p. 115
• Thermal · 2nd-degree 6.99 km Ch. 7 · Fig. 7.42 · p. 291
• Thermal · 3rd-degree 4.02 km Ch. 7 · Fig. 7.42 · p. 291

Outermost ring 9.93 km. Data: https://apocalab.com/blast-radius/ — the same JSON, the same figures, the same printed pages.

The rings are geodesic circles — true ground distances — projected onto the basemap, so at 60° of latitude they are visibly not the same shape as at the equator. Each one is drawn from a gazetteer point outward, which means what you see is the distance from that point, not a stylised target. What the map does not know is the ground itself: hills, shorelines, a dense core of buildings and a field of the same beige are all one surface here, and the manual's distances assume flat terrain at sea level. Nothing on this page corrects for that.

What the 5 psi ring means

Five psi is the overpressure the manual ties to most residential buildings being destroyed. On this map that ring sits at 1.71 km for 15 kt, 3.22 km for 100 kt and 6.93 km for 1 Mt, all of it from Fig. 3.73c on p. 115, read at 1 kt and multiplied by the cube root of the yield. The chart prints 1, 2, 4, 6, 8 and 10 psi contours and never 5, so each of those values is interpolated between the 4 and 6 psi curves: at 1 kt the 5 psi position is 2,275 ft from ground zero, at a burst height of 1,017 ft. The quantity is peak overpressure on the ground, which already contains the reflected shock — not the incident pressure in free air — so a tool quoting incident pressure will draw a visibly smaller ring under the same label.

What the 1 psi ring means

One psi is the weakest contour the chart draws and the one that reaches furthest; it is roughly where window glass breaks. The ring measures 5.28 km at 15 kt, 9.93 km (6.17 mi) at 100 kt and 21.40 km (13.30 mi) at 1 Mt, again from Fig. 3.73c, p. 115. It is also the most sensitive of the five to burst height: at 1 kt this contour reaches 7,020 ft when the burst is at 1,575 ft, against 3,830 ft for a contact burst — a factor of 1.8 from burst height alone. That sensitivity is why every ring here is read at the peak of its own curve instead of at one burst height chosen in advance; the contact-burst convention is the one stated on p. 106.

The fireball is not a thermal ring

The innermost ring is the fireball at the moment the shock front separates from it: 0.21 km at 100 kt, from R = 110·W^0.4 ft, Eq. (2.127.1) on p. 70. §2.129 notes it can later grow to about twice that radius, so the ring is a breakaway value, not a maximum. The thermal rings are a different claim: slant ranges to a given irradiance. 4.5 cal/cm² — second-degree burns on unshaded light skin — reaches 6.99 km at 100 kt and 16.68 km at 1 Mt; 10 cal/cm² — third-degree — 4.02 km and 10.35 km, both read directly off Fig. 7.42 (p. 291), computed at 200·W^0.4 ft with 12-mile visibility (§7.42, p. 290). No thermal ring is drawn for a contact burst: the manual handles that case by a separate route (§7.41, p. 290).

Why ten times the yield is not ten times the radius

For a given overpressure, distance scales as W^1/3 — the manual's own law, Eq. (3.61.2) on p. 101, restated in §3.62 (p. 102) and applied to these figures in §3.73 (p. 110). From 100 kt to 1 Mt that factor is 10^1/3 = 2.15, and the map shows it: the 5 psi ring goes from 3.22 km to 6.93 km, a factor of 2.15; the 1 psi ring from 9.93 km to 21.40 km, 2.16. Area grows with the square of the radius, so ten times the yield covers about 4.6 times the ground. That is why a 1 Mt ring is not ten times wider than a 100 kt ring, and why one zoom holds all three yields.

The 20 cities, and the population measure

The map offers 20 cities: New York, Los Angeles, Chicago, Houston, San Francisco, Washington, Miami, Seattle, Boston, Atlanta, London, Paris, Tokyo, Berlin, Sydney, Toronto, Mexico City, São Paulo, New Delhi and Johannesburg. Each centre is a GeoNames gazetteer point, not an administrative centroid: boundaries differ by country, so rings would not be comparable. A city is a place for the numbers, not a new set: every ring comes from Fig. 3.73c (p. 115) for blast and fireball, Fig. 7.42 (p. 291) for thermal. Population is not printed here yet; the convention is fixed — residents inside 10 km of that point on the WorldPop 1 km grid, 2020 estimates, with radius, year and dataset beside the number. Ring populations are a separate count, never merged into the city total. One city at a time, rings intact without scripting: the nuke simulator.

Where these numbers stop being readable

Three cells here sit at the edge of what Fig. 3.73c supports. Reading each contour at its peak puts the 1 Mt burst heights at 10,174 ft for 5 psi and 15,750 ft for 1 psi, and even the 100 kt 1 psi ring at 7,311 ft. The chart is computed for a homogeneous sea-level atmosphere at burst heights of 5,000 ft or less (§3.73, p. 110), so those rings extrapolate its assumption by up to a factor of three. They stay: dropping 1 Mt would hide the limit, not state it. No altitude correction (§3.64–3.66) is applied, which pushes them low, not high. Read them as the edge of what the chart supports; the trail is under where these numbers come from.

Yields covered: 15 kt · 100 kt · 1,000 kt. Cities: 20. Contact bursts are shown for the fireball and the two overpressure rings; thermal radii are not drawn for a contact burst, because Fig. 7.42 is an air-burst chart and the manual handles surface-burst heating by a separate route (§7.41, p. 290).