[meteorite-list] Meteorite Link of the Week #5 : Earth Impact Effects Program

From: Galactic Stone & Ironworks <meteoritemike_at_meteoritecentral.com>
Date: Mon, 21 Apr 2014 21:08:24 -0400
Message-ID: <CAKBPJW92AJfmsfP3oXwJfT6XNgYRcLWvnHXAar0X9FLkqcT0pw_at_mail.gmail.com>

Meteorite Link of the Week #5 - (http://impact.ese.ic.ac.uk/ImpactEffects/)

Purdue University and Imperial College of London - Earth Impact Effects Program

You can use this fun simulator to calculate the various effects of
meteorite impacts on Earth.

As a hypothetical witness, you can set your observing distance from
the impact site and the program will determine what the effects will
be based on your distance.

You can control many of the parameters, such as the composition,
velocity, and angle of the impactor. You can also set the type of
target material, such as rock or water. Put in the variables, click
"Calculate Effect", and you will be presented with tables of data.

For example :

Let us be a witness that is 10 miles from the impact site.

The impactor will be an iron meteorite with a diameter of 20 meters (look out!).

The velocity of the impactor will be 17 kilometers per second and the
angle of entry will be 45 degrees.

The target area will be composed of sedimentary rock.

This yields the following effects :


    Distance from Impact: 16.10 km ( = 10.00 miles )
    Projectile diameter: 20.00 meters ( = 65.60 feet )
    Projectile Density: 8000 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: 4.84 x 1015 Joules = 1.16 MegaTons TNT
    The average interval between impacts of this size somewhere on
Earth is 169.6 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 14100 meters = 46100 ft
    The projectile bursts into a cloud of fragments at an altitude of
3520 meters = 11500 ft
    The residual velocity of the projectile fragments after the burst
is 6.28 km/s = 3.9 miles/s
    The energy of the airburst is 4.18 x 1015 Joules = 1.00 x 100 MegaTons.
    Large fragments strike the surface and may create a crater strewn
field. A more careful treatment of atmospheric entry is required to
accurately estimate the size-frequency distribution of meteoroid
fragments and predict the number and size of craters formed.

Air Blast:

    The air blast will arrive approximately 49.9 seconds after impact.
    Peak Overpressure: 10200 Pa = 0.102 bars = 1.45 psi
    Max wind velocity: 23 m/s = 51.5 mph
    Sound Intensity: 80 dB (Loud as heavy traffic)
    Damage Description: Glass windows will shatter.

The shockwave from this impact would reach the observer almost 50
seconds after impact, arriving as a 51.5mph air-blast accompanied by
80-decibel sonics - strong enough to shatter windows.

You can learn more about the simulator and how it works by reading the
following PDF file -
http://impact.ese.ic.ac.uk/ImpactEffects/effects.pdf

Best regards,

MikeG


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Received on Mon 21 Apr 2014 09:08:24 PM PDT