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
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Your Inputs:
- Distance from Impact: 50.00 km ( = 31.10 miles )
- Projectile diameter: 153.00 meters ( = 503.00 feet )
- Projectile Density: 2450 kg/m3
- Impact Velocity: 20.00 km per second ( = 12.40 miles per second )
- Impact Angle: 90 degrees
- Target Density: 2500 kg/m3
- Target Type: Sedimentary Rock
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Energy:
- Energy before atmospheric entry: 9.24 x 1017 Joules = 2.21 x 102 MegaTons TNT
- The average interval between impacts of this size somewhere on Earth during the last 4 billion years is 1.6 x 104years
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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.
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Atmospheric Entry:
- The projectile begins to breakup at an altitude of 62700 meters = 206000 ft
- The projectile reaches the ground in a broken condition. The mass of projectile strikes the surface at velocity 16.9 km/s = 10.5 miles/s
- The energy lost in the atmosphere is 2.62 x 1017 Joules = 6.26 x 101 MegaTons.
- The impact energy is 6.62 x 1017 Joules = 1.58 x 102MegaTons.
- 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 0.474 km by 0.474 km
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Crater Dimensions:
- What does this mean?
- Crater shape is normal in spite of atmospheric crushing; fragments are not significantly dispersed.
- Transient Crater Diameter:
2.57 km ( = 1.59 miles )
- Transient Crater Depth: 907 meters ( = 2980 feet )
- Final Crater Diameter:
2.92 km ( = 1.81 miles )
- Final Crater Depth: 408 meters ( = 1340 feet )
- The crater formed is a simple crater
- The floor of the crater is underlain by a lens of broken rock debris (breccia) with a maximum thickness of 0 microns ( = 0 thousandths of an inch ).
- The volume of the target melted or vaporized is 0.0059 km3 = 0.00141 miles3
- Roughly half the melt remains in the crater
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Thermal Radiation:
- What does this mean?
- Time for maximum radiation: 103 milliseconds after impact
- Visible fireball radius: 1.55 km ( = 0.961 miles )
- The fireball appears 7.03 times larger than the sun
- Thermal Exposure: 1.08 x 105 Joules/m2
- Duration of Irradiation: 22.7 seconds
- Radiant flux (relative to the sun): 4.79
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Seismic Effects:
- What does this mean?
The major seismic shaking will arrive approximately 10 seconds after impact.- Richter Scale Magnitude: 6.1
- Mercalli Scale Intensity at a distance of 50 km:
VII. Damage negligible in buildings of good design and construction; slight to moderate in well-built ordinary structures; considerable damage in poorly built or badly designed structures; some chimneys broken.
VIII. Damage slight in specially designed structures; considerable damage in ordinary substantial buildings with partial collapse. Damage great in poorly built structures. Fall of chimneys, factory stacks, columns, monuments, walls. Heavy furniture overturned.
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Ejecta:
- What does this mean?
The ejecta will arrive approximately 1.69 minutes after the impact.- At your position there is a fine dusting of ejecta with occasional larger fragments
- Average Ejecta Thickness: 3.1 mm ( = 1.22 tenths of an inch )
- Mean Fragment Diameter: 11.1 cm ( = 4.39 inches )
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Air Blast:
- What does this mean?
The air blast will arrive approximately 2.53 minutes after impact.- Peak Overpressure: 9790 Pa = 0.0979 bars = 1.39 psi
- Max wind velocity: 22.2 m/s = 49.6 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