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: 100.00 km ( = 62.10 miles )
 Projectile diameter: 270.00 meters ( = 886.00 feet )
 Projectile Density: 3000 kg/m^{3}
 Impact Velocity: 20.00 km per second ( = 12.40 miles per second )
 Impact Angle: 45 degrees
 Target Density: 2500 kg/m^{3}
 Target Type: Sedimentary Rock

Energy:
 Energy before atmospheric entry: 6.18 x 10^{18} Joules = 1.48 x 10^{3} MegaTons TNT
 The average interval between impacts of this size somewhere on Earth during the last 4 billion years is 6.8 x 10^{4}years

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.

Atmospheric Entry:
 The projectile begins to breakup at an altitude of 56600 meters = 186000 ft
 The projectile reaches the ground in a broken condition. The mass of projectile strikes the surface at velocity 18.7 km/s = 11.6 miles/s
 The energy lost in the atmosphere is 7.68 x 10^{17} Joules = 1.83 x 10^{2} MegaTons.
 The impact energy is 5.42 x 10^{18} Joules = 1.29 x 10^{3}MegaTons.
 The larger of these two energies is used to estimate the airblast damage.
 The broken projectile fragments strike the ground in an ellipse of dimension 0.889 km by 0.628 km

Crater Dimensions:
 What does this mean?
 Crater shape is normal in spite of atmospheric crushing; fragments are not significantly dispersed.
 Transient Crater Diameter:
3.98 km ( = 2.47 miles )
 Transient Crater Depth: 1.41 km ( = 0.873 miles )
 Final Crater Diameter:
4.78 km ( = 2.97 miles )
 Final Crater Depth: 474 meters ( = 1550 feet )
 The crater formed is a complex crater.
 The volume of the target melted or vaporized is 0.0341 km^{3} = 0.00818 miles^{3}
 Roughly half the melt remains in the crater, where its average thickness is 2.75 meters ( = 9.01 feet ).

Thermal Radiation:
 What does this mean?
 Time for maximum radiation: 188 milliseconds after impact
 Visible fireball radius: 2.73 km ( = 1.69 miles )
 The fireball appears 6.2 times larger than the sun
 Thermal Exposure: 1.86 x 10^{5} Joules/m^{2}
 Duration of Irradiation: 45.6 seconds
 Radiant flux (relative to the sun): 4.07

Seismic Effects:
 What does this mean?
The major seismic shaking will arrive approximately 20 seconds after impact.  Richter Scale Magnitude: 6.7
 Mercalli Scale Intensity at a distance of 100 km:
VI. Felt by all, many frightened. Some heavy furniture moved; a few instances of fallen plaster. Damage slight.
VII. Damage negligible in buildings of good design and construction; slight to moderate in wellbuilt ordinary structures; considerable damage in poorly built or badly designed structures; some chimneys broken.

Ejecta:
 What does this mean?
The ejecta will arrive approximately 2.4 minutes after the impact.  At your position there is a fine dusting of ejecta with occasional larger fragments
 Average Ejecta Thickness: 2.23 mm ( = 0.878 tenths of an inch )
 Mean Fragment Diameter: 2.95 cm ( = 1.16 inches )

Air Blast:
 What does this mean?
The air blast will arrive approximately 5.05 minutes after impact.  Peak Overpressure: 9900 Pa = 0.099 bars = 1.41 psi
 Max wind velocity: 22.4 m/s = 50.1 mph
 Sound Intensity: 80 dB (Loud as heavy traffic)
 Damage Description:
Glass windows will shatter.
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.
Recent improvements in the airblast calculation are described here.
Earth Impact Effects Program Copyright 2004, Robert Marcus, H.J. Melosh, and G.S. Collins
These results come with ABSOLUTELY NO WARRANTY