Asteroid Impact Calculation

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Wed Dec 29 20:17:07 2004 Asteroid Impact Calculation
Posted by Tony Lawrence
Referencing: http://www.lpl.arizona.edu/impacteffects/

Recent news about near misses and "oops, what was THAT?" fly-bys piqued my curiousity about how damaging comets and asteroids can be. This calculator purports to provide some answers. Just for fun, I sent a large iron object hurtling into the Atlantic ocean near me.

The results:

Impact Effects

Robert Marcus, H. Jay Melosh, and Gareth Collins

Your Inputs:

Distance from Impact: 241.50 km = 149.97 miles

Projectile Diameter: 1609.34 m = 5278.64 ft = 1.00 miles

Projectile Density: 8000 kg/m³

Impact Velocity: 17.00 km/s = 10.56 miles/s

Impact Angle: 45 degrees

Target Density: 1000 kg/m³

Target Type: Liquid Water of depth 91.44 meters, over typical rock.

Energy:

Energy before atmospheric entry: 2.52 x 10²¹ Joules = 6.03 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:

What does this mean?

The crater opened in the water has a diameter of 33.9 km = 21 miles

For the crater formed in the seafloor:

Transient Crater Diameter: 20.6 km = 12.8 miles

Transient Crater Depth: 7.28 km = 4.52 miles

Final Crater Diameter: 30.7 km = 19 miles

Final Crater Depth: 0.829 km = 0.515 miles

The crater formed is a complex crater.

The volume of the target melted or vaporized is 15.4 km³ = 3.69 miles³

Roughly half the melt remains in the crater , where its average thickness is 46.2 meters = 152 feet

Thermal Radiation:

What does this mean?

Time for maximum radiation: 1.6 seconds after impact

Visible fireball radius: 22.6 km = 14 miles

The fireball appears 21.3 times larger than the sun

Thermal Exposure: 1.62 x 10⁶ Joules/m²

Duration of Irradiation: 35.3 seconds

Radiant flux (relative to the sun): 45.8

Effects of Thermal Radiation:

Much of the body suffers first degree burns

Seismic Effects:

What does this mean?


The major seismic shaking will arrive at approximately 48.3 seconds.

Richter Scale Magnitude: 8.5

Mercalli Scale Intensity at a distance of 241.5 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.

Ejecta:

What does this mean?


The ejecta will arrive approximately 227 seconds after the impact.

Average Ejecta Thickness: 11.4 cm = 4.48 inches

Mean Fragment Diameter: 1.94 cm = 0.762 inches

Air Blast:

What does this mean?


The air blast will arrive at approximately 732 seconds.

Peak Overpressure: 76900 Pa = 0.769 bars = 10.9 psi

Max wind velocity: 141 m/s = 315 mph

Sound Intensity: 98 dB (May cause ear pain)

Damage Description:

Multistory wall-bearing buildings will collapse.

Wood frame buildings will almost completely collapse.

Glass windows will shatter.

Up to 90 percent of trees blown down; remainder stripped of branches and leaves.

Tell me more...

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

Comments /Blog/B1215.html
CommentsBlog1215 :

You just better hope that asteroid thingy doesn't splash down anytime soon. You'd literally be blown out of the water.

--BigDumbDinosaur

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