Asteroid Impact Simulator for Any City
Five real impactors are built in, from the 19-metre Chelyabinsk meteor to the 10-kilometre Chicxulub asteroid, and every parameter is yours to change. Pick a target, load a preset or set your own object, and read the crater, fireball, burn radii, and 20, 5, and 1 psi blast rings straight off the map.
10⁵ m · ≈ 200 km (impact effects) · MapLibre · Physics model
Loading the impact map…
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Presets, parameters, rings
Five real impactors, one map
The presets span roughly eight orders of magnitude in energy. Chelyabinsk was a 19-metre stony body that broke apart about 30 km above Russia in 2013. Tunguska, about 55 metres of porous rock, flattened Siberian forest in 1908 without leaving a crater. The 50-metre iron mass behind Arizona’s Meteor Crater did reach the ground. Apophis stands in for a 370-metre near-Earth asteroid, and Chicxulub is the 10 km object linked to the end of the dinosaurs. Load any of them, then start moving sliders.
Three settings that change everything
- Composition sets density: ice at 1,000 kg/m³, porous rock at 1,500, dense rock at 3,000, iron at 8,000. Switching from ice to iron makes the same object eight times heavier.
- Speed enters squared. An object arriving at 30 km/s carries more than twice the energy of the same object at 20 km/s.
- Entry angle decides how much atmosphere the object crosses. Shallow entries, like Chelyabinsk’s 18°, favour breakup high in the air.
Reading the results
The summary reports energy in megatons of TNT and in Hiroshima equivalents, then says whether the object airbursts or reaches the ground. Ground impacts get a crater diameter. Every run gets a fireball radius, three thermal-burn radii, the 20, 5, and 1 psi blast rings, a peak wind speed, and an earthquake magnitude, all drawn outward from the point you chose.
Why the same diameter can mean no crater or a deep hole
A meteor decelerates against the air like a car hitting water. When the dynamic pressure exceeds the body’s strength it fragments, and the fragments shed their energy in a burst before they land. Stony objects a few tens of metres across usually end this way; the map then shows burn and blast rings around an airburst point with no crater. Iron is stronger and denser, which is why a 50-metre iron mass excavated Meteor Crater while the larger Tunguska body left only fallen trees. Above a few hundred metres, almost everything reaches the ground regardless of material.
Where the numbers come from
The calculations follow the Earth Impact Effects Program published by Collins, Melosh, and Marcus in 2005: atmospheric entry and breakup, crater scaling laws, a fireball thermal model, seismic magnitude derived from impact energy, and overpressure rings fitted to nuclear-test data. The population setting only scales the number of people the rings enclose; the physics never changes. You can place the target by tapping the map, using the arrow keys, choosing a city, or sharing your location, and export the finished map as an image.
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Questions about the impact model
What does this asteroid impact simulator calculate?
For the diameter, speed, entry angle, and composition you set, it estimates the impact energy in megatons of TNT and Hiroshima equivalents, whether the object airbursts or reaches the ground, the crater size, the fireball, three thermal-burn radii, the 20, 5, and 1 psi blast rings, peak wind speed, and an earthquake magnitude.
How is the impact energy worked out?
As kinetic energy: half the mass times the speed squared. Mass comes from the diameter and the density of the chosen material, from about 1,000 kg/m³ for ice to 8,000 kg/m³ for iron, which is why switching composition changes the rings more than a small change in diameter does.
Why do small asteroids leave no crater?
The atmosphere breaks them up. A stony object a few tens of metres across usually fragments and releases its energy as an airburst kilometres above the ground, as Chelyabinsk did in 2013 and Tunguska did in 1908. Iron bodies survive entry more often, which is how the 50 m impactor behind Arizona's Meteor Crater reached the surface.
How large was the asteroid that ended the dinosaurs?
The Chicxulub impactor is estimated at roughly 10 km across. The simulator's Chicxulub preset uses 10 km of dense rock at 20 km/s and a 45° entry, which works out to roughly 75 million megatons of TNT. Impacts of that class recur on timescales of tens of millions of years.
Which model is behind the numbers?
The Earth Impact Effects Program by Collins, Melosh, and Marcus (2005): atmospheric entry and breakup, crater scaling laws, a fireball thermal model, seismic magnitude from impact energy, and overpressure rings fitted to nuclear-test data. It assumes a flat land target.
How much should I trust the rings?
Treat them as order-of-magnitude estimates. Airbursts and very large impacts carry the biggest uncertainties, and the model does not cover ocean impacts, tsunamis, ejecta fallout, or climate effects. It is built for understanding scale, not for emergency planning.
Order-of-magnitude educational estimates for a flat land target. Not a forecast of any real event.