Impact Effects

Credit: Robert Marcus, H. Jay Melosh, and Gareth Collins

Please note: the results below are estimates based on current (limited) understanding of the impact process and come with large uncertainties; they should be used with caution, particularly in the case of peculiar input parameters. All values are given to three significant figures but this does not reflect the precision of the estimate.

IMPACT 1

Your Inputs:
Distance from Impact: 10.00 km = 6.21 miles
Projectile Diameter: 2000.00 m = 6560.00 ft = 1.24 miles
Projectile Density: 3000 kg/m³
Impact Velocity: 20.00 km/s = 12.42 miles/s
Impact Angle: 45 degrees
Target Density: 2500 kg/m³
Target Type: Sedimentary Rock

Energy:
Energy before atmospheric entry: 2.51 x 10²¹ Joules = 6.00 x 10⁵ MegaTons TNT
The average interval between impacts of this size somewhere on Earth during the last 4 billion years is 3.1 x 10⁶years

Major Global Changes:
The Earth is not strongly disturbed by the impact and loses negligible mass.
The impact does not make a noticeable change in the Earth's rotation period or the tilt of its axis.
The impact does not shift the Earth's orbit noticeably.

Crater Dimensions:
Transient Crater Diameter: 19.5 km = 12.1 miles
Transient Crater Depth: 6.89 km = 4.28 miles
Final Crater Diameter: 28.8 km = 17.9 miles
Final Crater Depth: 0.814 km = 0.506 miles
The crater formed is a complex crater.
The volume of the target melted or vaporized is 15.7 km³ = 3.77 miles³
Roughly half the melt remains in the crater, where its average thickness is 52.7 meters = 173 feet

Thermal Radiation:
Time for maximum radiation: 1.36 seconds after impact
Your position is inside the fireball.
The fireball appears 617 times larger than the sun
Thermal Exposure: 1.19 x 10¹⁰ Joules/m²
Duration of Irradiation: 353 seconds
Radiant flux (relative to the sun): 33800

Effects of Thermal Radiation: Clothing ignites Much of the body suffers third degree burns Newspaper ignites Plywood flames Deciduous trees ignite Grass ignites

Seismic Effects: The major seismic shaking will arrive at approximately 2 seconds.
Richter Scale Magnitude: 8.5
Mercalli Scale Intensity at a distance of 10 km:
X. Most masonry and frame structures destroyed with their foundations. Some well-built wooden structures and bridges destroyed. Serious damage to dams, dikes, embankments. Large landslides. Water thrown on banks of canals, rivers, lakes, etc. Sand and mud shifted horizontally on beaches and flat land. Rails bent slightly. XI. As X. Rails bent greatly. Underground pipelines completely out of service.

Ejecta:
The ejecta will arrive approximately 45.2 seconds after the impact.
Your position is beneath the continuous ejecta deposit.
Average ejecta Thickness: 1290 m = 4230 ft

Air Blast: The air blast will arrive at approximately 30.3 seconds.
Peak Overpressure: 8.79x107 Pa = 879 bars = 12500 psi
Max wind velocity: 7540 m/s = 16900 mph
Sound Intensity: 159 dB (Dangerously Loud)

Damage Description:
Multistory wall-bearing buildings will collapse. Wood frame buildings will almost completely collapse. Multistory steel-framed office-type buildings will suffer extreme frame distortion, incipient collapse. Highway truss bridges will collapse. Highway girder bridges will collapse. Glass windows will shatter. Cars and trucks will be largely displaced and grossly distorted and will require rebuilding before use. Up to 90 percent of trees blown down; remainder stripped of branches and leaves

IMPACT 2

Your Inputs:
Distance from Impact: 10.00 km = 6.21 miles
Projectile Diameter: 2000.00 m = 6560.00 ft = 1.24 miles
Projectile Density: 3000 kg/m³
Impact Velocity: 50.00 km/s = 31.05 miles/s
Impact Angle: 45 degrees
Target Density: 2500 kg/m³
Target Type: Sedimentary Rock

Energy:
Energy before atmospheric entry: 1.57 x 10²² Joules = 3.75 x 10⁶ MegaTons TNT
The average interval between impacts of this size somewhere on Earth during the last 4 billion years is 1.3 x 10⁷years

Major Global Changes:
The Earth is not strongly disturbed by the impact and loses negligible mass.
The impact does not make a noticeable change in the Earth's rotation period or the tilt of its axis.
The impact does not shift the Earth's orbit noticeably.

Crater Dimensions:
Transient Crater Diameter: 29.2 km = 18.1 miles
Transient Crater Depth: 10.3 km = 6.4 miles
Final Crater Diameter: 45.5 km = 28.2 miles
Final Crater Depth: 0.934 km = 0.58 miles
The crater formed is a complex crater.
The volume of the target melted or vaporized is 98.3 km³ = 23.6 miles³
Roughly half the melt remains in the crater , where its average thickness is 147 meters = 483 feet

Ejecta:
Your position was inside the transient crater and ejected upon impact

IMPACT 3

Your Inputs:
Distance from Impact: 10.00 km = 6.21 miles
Projectile Diameter: 2000.00 m = 6560.00 ft = 1.24 miles
Projectile Density: 3000 kg/m³
Impact Velocity: 70.00 km/s = 43.47 miles/s
Impact Angle: 45 degrees
Target Density: 2500 kg/m³
Target Type: Sedimentary Rock

Energy:
Energy before atmospheric entry: 3.08 x 1022 Joules = 7.35 x 106 MegaTons TNT
The average interval between impacts of this size somewhere on Earth during the last 4 billion years is 2.1 x 107years

Major Global Changes:
The Earth is not strongly disturbed by the impact and loses negligible mass.
The impact does not make a noticeable change in the Earth's rotation period or the tilt of its axis.
The impact does not shift the Earth's orbit noticeably.

Crater Dimensions: Transient Crater Diameter: 33.8 km = 21 miles
Transient Crater Depth: 12 km = 7.43 miles
Final Crater Diameter: 53.8 km = 33.4 miles
Final Crater Depth: 0.982 km = 0.61 miles
The crater formed is a complex crater.
The volume of the target melted or vaporized is 193 km³ = 46.2 miles³
Roughly half the melt remains in the crater , where its average thickness is 214 meters = 703 feet

Ejecta:

Your position was inside the transient crater and ejected upon impact

IMPACT 4

Your Inputs:
Distance from Impact: 20.00 km = 12.42 miles
Projectile Diameter: 200000.00 m = 656000.00 ft = 124.20 miles
Projectile Density: 3000 kg/m³
Impact Velocity: 50.00 km/s = 31.05 miles/s
Impact Angle: 45 degrees
Target Density: 2500 kg/m³
Target Type: Sedimentary Rock

Energy:
Energy before atmospheric entry: 1.57 x 10²⁸ Joules = 3.75 x 10¹² MegaTons TNT
The average interval between impacts of this size is longer than the Earth's age.
Such impacts could only occur during the accumulation of the Earth, between 4.5 and 4 billion years ago.

Major Global Changes:
The Earth is not strongly disturbed by the impact and loses negligible mass.
The impact does not make a noticeable change in the Earth's rotation period or the tilt of its axis.
The impact does not shift the Earth's orbit noticeably.

Crater Dimensions:
Transient Crater Diameter: 1060 km = 658 miles
Transient Crater Depth: 375 km = 233 miles
Final Crater Diameter: 2640 km = 1640 miles
Final Crater Depth: 3.17 km = 1.97 miles
The crater formed is a complex crater.
The volume of the target melted or vaporized is 9.88X10⁷ km³ = 2.37X10⁷ miles³
Roughly half the melt remains in the crater , where its average thickness is 112 km = 69.5 miles

See: http://www.lpl.arizona.edu/~marcus/CollinsEtAl2005.pdf for the mathematics and http://www.lpl.arizona.edu/impacteffects/ for the actual program.

ASTEROID 2004 MN

An edited version of the 2004 MN4 story originally posted on SPACE.com at 9:58 a.m. ET on Dec. 24:
Scientists said Thursday that a recently discovered asteroid has a chance of hitting Earth in the year 2029, but that further observations would likely rule out the impact scenario.
The asteroid is named 2004 MN4. It was discovered in June and spotted again this month. It is about a quarter mile (400 meters) wide
2004 MN4 is now being tracked very carefully by many astronomers around the world, and we continue to update our risk analysis for this object. Today's impact monitoring results indicate that the impact probability for April 13, 2029 has risen to about 1.6 percent, which for an object of this size corresponds to a rating of 4 on the ten-point Torino Scale. Nevertheless, the odds against impact are still high, about 60-to-1, meaning that there is a better than 98 percent chance that new data in the coming days, weeks, and months will rule out any possibility of impact in 2029.
With a half-dozen or so other asteroid discoveries dating back to 1997, scientists had announced long odds of an impact -- generating frightening headlines in some cases -- only to announce within hours or days that the impact chances had been reduced to zero by further observations. Experts have said repeatedly that they are concerned about alarming the public before enough data is gathered to project an asteroid's path accurately.
Asteroid 2004 MN4 is an unusual case in that follow-up observations have caused the risk assessment to climb -- from Torino level 2 to 4 -- rather than fall.