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Impact Effects Calculator
Pick an impact site, choose an asteroid, and map the crater, fireball, thermal burns, and blast zones with the Collins, Melosh & Marcus impact-effects model.
Asteroid Impact Simulator
This asteroid impact simulator lets you drop a meteor anywhere on an interactive map and watch the devastation spread as concentric effect zones. Choose the asteroid's diameter, speed, impact angle, and composition — ice, rock, or iron — and the tool models the impact energy, crater, fireball, thermal burns, air-blast overpressure, peak winds, and earthquake magnitude.
The simulator implements the Earth Impact Effects Program of Collins, Melosh, and Marcus (2005). It first models atmospheric entry to decide whether the asteroid reaches the ground or detonates as an airburst, then applies crater-scaling laws, a fireball thermal model, the Gutenberg–Richter energy relation for seismic magnitude, and nuclear-test blast data for the overpressure rings.
The rings are drawn outward from the impact point. The crater and fireball sit at the center, surrounded by thermal-radiation zones (third-, second-, and first-degree burns) and air-blast overpressure rings: about 20 psi where reinforced and steel-framed buildings collapse, 5 psi where most homes and buildings collapse, and 1 psi where windows shatter and injuries become widespread.
It estimates the consequences of an asteroid striking Earth — the impact energy in megatons of TNT, the crater size, the fireball radius, the thermal radiation zones that cause burns, the air-blast overpressure rings, the peak wind speed, and the seismic magnitude — based on the asteroid size, speed, impact angle, and composition you choose.
Impact energy is the kinetic energy of the asteroid, one half times its mass times its velocity squared. The mass comes from the diameter and density (an iron asteroid is far heavier than an icy one of the same size). The energy is then expressed in megatons of TNT for comparison: one megaton equals 4.184 × 10^15 joules.
Small or low-density asteroids break apart in the atmosphere and release their energy as an airburst before reaching the ground, so no crater forms — the 2013 Chelyabinsk and 1908 Tunguska events were airbursts. Larger or denser bodies, especially iron ones, keep enough momentum to hit the surface and excavate a crater.
The Chicxulub impactor that ended the age of dinosaurs about 66 million years ago is estimated at roughly 10 kilometers across and released on the order of 100 million megatons of TNT. Impacts that large occur only every hundred million years or so, while city-threatening impacts of tens of meters are far more frequent.
The calculations follow the Earth Impact Effects Program published by Gareth Collins, Jay Melosh, and Robert Marcus in 2005, which combines atmospheric-entry physics, crater-scaling laws from experiments and nuclear tests, fireball thermal radiation, and air-blast data into a single set of equations.
The results are order-of-magnitude estimates with large uncertainties, particularly for airburst blast effects and very large impacts. The model assumes a land target and does not include ocean impacts, tsunamis, ejecta fallout, or long-term climate effects, so it is best used for education rather than emergency planning.