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: 10.00 km ( = 6.21 miles )
Projectile diameter: 1.25 km ( = 0.78 miles )
Projectile Density: 3000 kg/m3
Impact Velocity: 8.00 km per second ( = 4.97 miles per second )
Impact Angle: 90 degrees
Target Density: 3000 kg/m3
Target Type: Crystalline Rock

Energy:

Energy before atmospheric entry: 9.82 x 1019 Joules = 2.35 x 104 MegaTons TNT
The average interval between impacts of this size somewhere on Earth during the last 4 billion years is 3.8 x 105years

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).
The impact does not shift the Earth's orbit noticeably.

Crater Dimensions:

What does this mean?


Transient Crater Diameter: 9.53 km ( = 5.92 miles )
Transient Crater Depth: 3.37 km ( = 2.09 miles )

Final Crater Diameter: 12.9 km ( = 7.98 miles )
Final Crater Depth: 638 meters ( = 2090 feet )
The crater formed is a complex crater.
At this impact velocity ( < 12 km/s), little shock melting of the target occurs.

Thermal Radiation:

What does this mean?


At this impact velocity ( < 15 km/s), little vaporization occurs; no fireball is created, therefore, there is no thermal radiation damage.

Seismic Effects:

What does this mean?


The major seismic shaking will arrive approximately 2 seconds after impact.
Richter Scale Magnitude: 7.5
Mercalli Scale Intensity at a distance of 10 km:


Ejecta:

What does this mean?


The ejecta will arrive approximately 45.2 seconds after the impact.
Your position is beneath the continuous ejecta deposit.
Average Ejecta Thickness: 73.7 meters ( = 242 feet )
Mean Fragment Diameter: 36.5 meters ( = 120 feet )

Air Blast:

What does this mean?


The air blast will arrive approximately 30.3 seconds after impact.
Peak Overpressure: 7.43e+06 Pa = 74.3 bars = 1060 psi
Max wind velocity: 2180 m/s = 4870 mph
Sound Intensity: 137 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