The Chicxulub Impact

Step 0 · Late Cretaceous · ~66.0 million years ago

The world before the last day

The late Cretaceous world was warmer than today and sea levels were high. Dinosaurs had dominated life on land for more than 160 million years. The target was a shallow sea over what is now the Yucatán Peninsula in Mexico. The seafloor there was limestone and sulfur-rich evaporite rock, which later made the climate effects far worse.

Impact site

21.3°N 89.5°W

Beneath the village of Chicxulub, Yucatán Peninsula

Age

~66.0 million yr

The K–Pg boundary (Cretaceous–Paleogene)

Geography that differed from today

North and South America were not yet joined

The Central American Seaway was open, so the tsunami could pass straight into the Pacific.

The globe uses NASA Blue Marble satellite imagery adjusted toward the Cretaceous: the polar ice is removed (Greenland and Antarctica are shown forested) and the Central American Seaway is opened. The continents are still in their present-day positions, which differed slightly 66 million years ago.

How to use: pick a step below the globe or press ← →. ▶ plays the events within a step. Drag the globe to move the camera yourself. “▶ Play full film” runs every step in sequence, full screen.

Step 1 · T − 10 minutes → T − 0

The asteroid approaches

A carbonaceous (C-type) asteroid that formed beyond the orbit of Jupiter came in from the north-east at roughly 60° to the ground and about 20 km per second. It crossed the ~100 km of atmosphere in under six seconds, compressing the air ahead of it into incandescent plasma.

Diameter

~10–15 km

Models use 12–17 km. Taller than Everest (8.8 km)

Speed

~20 km/s

≈ 72,000 km/h, about 100 times an airliner

Angle and direction

~60° from NE

The angle that threw the most vapour into the upper atmosphere

Time through the atmosphere

~5.8 s

100 km ÷ (20 km/s × sin 60°)

Type of object

Carbonaceous chondrite

Confirmed from ruthenium isotopes in the K–Pg layer (Fischer-Gödde et al., 2024). Not a comet.

When the front of the asteroid touched the sea, its back was still at about the cruising altitude of an airliner. In this scene the object is enlarged ×3 so it can be seen. Distances and speed are to scale, and the final seconds are stretched into slow motion.

Sources: Collins et al. 2020 (Nature Communications); Fischer-Gödde et al. 2024 (Science)

Step 2 · T = 0 → T + 10 minutes

The impact and the crater

All of the asteroid's kinetic energy was released in a fraction of a second. Rock and seawater vaporised into an enormous fireball. Within seconds a cavity more than 20 km deep opened (some models reach about 28 km). Its walls then collapsed, the floor rebounded upward and fell back into a ring of peaks. The final crater was 180–200 km wide and about 3 km deep, and the whole process took only a few minutes.

Energy

~10²³–5×10²³ J

The most commonly used value is about 10²³ J

TNT equivalent

24–120 million Mt

1 Mt = 4.184×10¹⁵ J

Hiroshima bombs

1.6–8 billion

Hiroshima ≈ 15 kt

Final crater

180–200 km

Now buried under sediment and invisible at the surface

Crater sequence

Transient cavity 20–28 km deep → collapses to ~3 km

Gravity pulled the walls down and the floor rebounded, like a drop of water splashing back up, but in solid rock.

In the 3D scene the fireball and smoke column rise from the impact point, the transparent shell is the shock wave in the air, bright points are ejected rock, and the blue ring is seawater pushed outward by the curtain of debris.

Sources: Range et al. 2022 (AGU Advances) via Physics Today; Schulte et al. 2010; GSA 2022

Step 3 · T + 1 minute → weeks

Shock waves and a mega-earthquake

A curtain of debris tens of kilometres high pushed the sea outward into a rim wave about 4.5 km high within 2.5 minutes of impact, before it collapsed as the debris fell back. At the same time seismic waves travelled through the planet and reached the opposite side in about 20 minutes.

Seismic energy

~10²³ J

Estimated from sediment evidence

vs Sumatra 2004 (M9.1)

~50,000×

The quake behind the Indian Ocean tsunami

Rim wave

4.5 km

At T + 2.5 minutes, from simulations

Duration of shaking

Weeks–months

Faults continue up into the spherule layer that settled later

Evidence in the rocks

• Colombia Gorgonilla Island: mud and sand layers 10–15 m below the ancient seafloor were deformed
• Mexico El Papalote: liquefaction, where water-saturated sediment was shaken until it flowed like a liquid
• USA Mississippi, Alabama and Texas: faults and cracks in the rock layers

The blue ring is the P-wave front (fastest), the violet ring the slower S-wave. Timings are approximate, for teaching purposes.

Sources: Bermúdez, GSA Connects 2022; Range et al. 2022

Step 4 · T + 10 minutes → T + 48 hours

A global mega-tsunami

Ten minutes after impact, a ring-shaped wave about 1.5 km high, 220 km from the impact point, began spreading in all directions. Its initial energy was up to about 30,000 times that of the 2004 Indian Ocean tsunami, strong enough to scour seafloor sediments half a world away.

The wave's path (Range et al., 2022)

• 1.5 km wave, 220 km from the impact
• Leaves the Gulf of Mexico for the North Atlantic
• Passes the Central American Seaway into the Pacific
• Crosses most of the Pacific and Atlantic and enters the Indian Ocean from both sides
• Reaches nearly every coastline on Earth

Open water, Gulf of Mexico

> 100 m

Wave height in the open ocean

Near North Atlantic coasts

> 10 m

Also parts of South America's Pacific coast

In shallow water

The wave grows much taller (shoaling)

Waves slow down and pile up as the seafloor rises, so heights at the coast were several times the open-ocean values.

Evidence: K–Pg sediments on the eastern shores of New Zealand's North and South Islands, more than 12,000 km from the crater, are disturbed and incomplete, and giant buried sand ripples in Louisiana were formed by these waves.

Reading the globe: the bright line is the wave front and the colour on the ocean is the approximate open-ocean wave height. Tap or click a point on the sea to see the distance by water, the arrival time and the approximate height. Values come from the shortest sea path at a constant ~790 km/h and a height decay tuned to the published figures. They are not output from the original model.

Source: Range et al. 2022, “The Chicxulub Impact Produced a Powerful Global Tsunami”, AGU Advances 3(5)

Step 5 · T + 15 minutes → hours

Fire from the sky

Molten rock thrown beyond the atmosphere fell back across the globe as billions of tiny glass beads (spherules). Friction with the air heated them intensely, the sky glowed red and radiated heat to the ground, wildfires broke out in many regions, and enormous amounts of soot rose into the atmosphere.

Tanis site

~3,000 km

From the impact, in North Dakota, USA

Season

Spring

Northern Hemisphere, from fossil fish bones at Tanis

A worldwide fingerprint

A thin clay layer unusually rich in iridium

Iridium is rare in Earth's crust but common in meteorites. This was the first clue to the impact theory (Alvarez, 1980).

At Tanis, fish were found with impact spherules lodged in their gills, which means the beads landed shortly after the impact while the fish were still alive.

Open question: whether the wildfires were global or regional is still debated. This model shows fire intensity falling with distance from the impact.

Sources: DePalma et al. 2019 (PNAS); During et al. 2022 (Nature); Alvarez et al. 1980 (Science)

Step 6 · weeks → ~10 years

Impact winter

Fine rock dust, soot from the fires and sulfur aerosols blanketed the atmosphere. Sunlight reaching the ground fell to about 1% for nearly two years. Photosynthesis almost stopped and food chains collapsed from the base.

Qualitative curves built from figures in several studies. Results vary between models depending on assumptions about the amount of dust, grain size, soot and sulfur.

Sunlight at the surface

~1%

For nearly 2 years (soot model)

Photosynthesis halted

~620 days

Back to pre-impact levels in about 3–4 years

Global mean temperature

down ~15 °C

Some models give different values

Fine dust aloft

up to ~15 years

Sulfate effects lasted about 10 years

Earlier work treated sulfur as the main driver. A 2023 study that measured dust grain sizes at Tanis suggests fine silicate dust played a larger role than previously thought.

Sources: Senel et al. 2023 (Nature Geoscience); Tabor et al. 2020 (GRL); Brugger et al. 2017

Step 7 · months → millions of years

Extinction and survival

When plants and plankton stopped growing, the herbivores starved, followed by the carnivores. Around 75% of species on Earth went extinct. Most survivors were small, lived in burrows or fresh water, and ate detritus or seeds that remained available through the dark.

Extinct

Non-avian dinosaurs Pterosaurs Mosasaurs Plesiosaurs Ammonites Many plankton groups

Survived

Birds (the surviving dinosaurs) Small mammals Crocodilians Turtles Frogs Ferns

Species lost

~75%

On land and in the sea

Life back in the crater

Within years

Plankton fossils in cores from the Chicxulub crater

“Fern spike”

Fern spores surge in the rocks just above the K–Pg boundary

Ferns were the first plants to recolonise devastated ground.

The ecological space left by the dinosaurs let mammals diversify rapidly in the Paleogene, eventually leading to primates and humans.

Sources: Schulte et al. 2010 (Science); Lowery et al. 2018 (Nature)

Step 8 · 1978 → today

How we know

• 1978 Geophysicists working for the oil company Pemex find a huge circular structure under Yucatán in gravity and magnetic data
• 1980 Luis and Walter Alvarez's team find abnormally high iridium in the K–Pg boundary layer and propose an extraterrestrial impact
• 1991 Hildebrand and colleagues identify the 180–200 km structure under Yucatán as the missing crater
• 2016 IODP–ICDP Expedition 364 drills into the crater's peak ring
• 2020 3D simulations show the impactor came from the north-east at about 60°
• 2022 First global tsunami simulation, and evidence of a mega-earthquake
• 2024 Ruthenium isotopes confirm a carbonaceous asteroid from beyond Jupiter

Calculator: what if the asteroid were different?

Diameter Impact speed Angle to the ground Object type (density) Mass Kinetic energy TNT equivalent Hiroshima bombs Approximate final crater (real Chicxulub: 180–200 km)

Formula: E = ½mv². Crater size uses the scaling equations of Collins, Melosh & Marcus (2005) from the Earth Impact Effects Program, assuming a sedimentary target of 2,500 kg/m³. A rough estimate for teaching purposes.

Sources

University of Michigan: the Chicxulub tsunami simulation (Range et al., 2022) Physics Today: how the tsunami and transient cavity formed Imperial College London: the 60° impact angle (Collins et al., 2020) Natural History Museum: an asteroid from beyond Jupiter (2024) Geological Society of America: the mega-earthquake (2022) Smithsonian: soot and darkness Smithsonian: fine dust and the impact winter (Senel et al., 2023) NASA Visible Earth: the Blue Marble imagery used for the globe

The full-screen stills in each step are AI-generated to help the imagination. They are not scientific reconstructions, and details of the animals and plants may not match the fossil record.