Earth Impact Effects Program

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. For more information about the uncertainty associated with our calculations and a full discussion of this program, please refer to this article

Your Inputs:

Distance from Impact: 500.00 km ( = 311.00 miles )
Projectile diameter: 100.00 km ( = 62.10 miles )
Projectile Density: 3000 kg/m3
Impact Velocity: 17.00 km per second ( = 10.60 miles per second )
Impact Angle: 45 degrees
Target Density: 2500 kg/m3
Target Type: Sedimentary Rock

Energy:

Energy before atmospheric entry: 2.27 x 1026 Joules = 5.42 x 1010 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 tilt of Earth's axis (< 5 hundreths of a degree).
Depending on the direction and location of impact, the collision may cause a change in the length of the day of up to 1.47 seconds.
The impact does not shift the Earth's orbit noticeably.

Crater Dimensions:

What does this mean?


Transient Crater Diameter: 384 km ( = 239 miles )
Transient Crater Depth: 136 km ( = 84.4 miles )

Final Crater Diameter: 838 km ( = 520 miles )
Final Crater Depth: 2.24 km ( = 1.39 miles )
The crater formed is a complex crater.
The volume of the target melted or vaporized is 1.43e+06 km3 = 343000 miles3
Roughly half the melt remains in the crater, where its average thickness is 12.3 km ( = 7.65 miles ).

Thermal Radiation:

What does this mean?


Time for maximum radiation: 1.2 minutes after impact

Your position is inside the fireball.
The fireball appears 546 times larger than the sun
Thermal Exposure: 4.25 x 1011 Joules/m2
Duration of Irradiation: 4.4 hours
Radiant flux (relative to the sun): 26800

Effects of Thermal Radiation:

Seismic Effects:

What does this mean?


The major seismic shaking will arrive approximately 1.67 minutes after impact.
Richter Scale Magnitude: 11.8 (This is greater than any earthquake in recorded history)
Mercalli Scale Intensity at a distance of 500 km:


Ejecta:

What does this mean?


The ejecta will arrive approximately 5.57 minutes after the impact.
Your position is beneath the continuous ejecta deposit.
Average Ejecta Thickness: 1.56 km ( = 0.966 miles )
Mean Fragment Diameter: 8.48 cm ( = 3.34 inches )

Air Blast:

What does this mean?


The air blast will arrive approximately 25.3 minutes after impact.
Peak Overpressure: 6.89e+07 Pa = 689 bars = 9780 psi
Max wind velocity: 6680 m/s = 14900 mph
Sound Intensity: 157 dB (Dangerously Loud)
Damage Description:


Tell me more...

Click here for a pdf document that details the observations, assumptions, and equations upon which this program is based. It describes our approach to quantifying the important impact processes that might affect the people, buildings, and landscape in the vicinity of an impact event and discusses the uncertainty in our predictions. The processes included are: atmospheric entry, impact crater formation, fireball expansion and thermal radiation, ejecta deposition, seismic shaking, and the propagation of the atmospheric blast wave.






Earth Impact Effects Program Copyright 2004, Robert Marcus, H.J. Melosh, and G.S. Collins
These results come with ABSOLUTELY NO WARRANTY