PSN-L Email List Message

Subject: Re: Mystery event
From: Brad Douglas rez@..................
Date: Tue, 18 Sep 2007 21:39:01 -0700

On Wed, 2007-09-19 at 15:36 +1200, Mark Robinson wrote:
> Brad Douglas wrote:
> > On Tue, 2007-09-18 at 16:56 -0700, Bob Hancock wrote:
> >> I believe there are some physicists that follow this site.  I would like to
> >> know what they think about the energy involved to make a crater 30 meters
> >> across and 6 meters deep, and how that would translate into magnitude.
> > 
> > A 5m crater releases on the order of 4.2-4.6GJ of energy equivalent to a
> > Richter M2.
> > 
> > There is little literature on craters of this size, so a little
> > extrapolation is in order.  I would say a 30mx6m crater would generate
> > no more than a M3.
> Computing Projectile Size from Crater Diameter

Nice find!  I've used similar pages before, but was not able to re-find
from a quick Google search, so I had to revert to my GSA handbook of
meteor impacts, which only covers large impacts.

Using the above URL, it estimates (using conservative values) energy
release of 20.29TJ (5.48kT TNT), which is ~M4.2.  That seems overly
large.  Was the impact, itself, recorded by seismometers?

> Scientist Confirms Meteorite in Puno, Peru is a Chondrite
> >

Good info.  Has anyone found reports of eyewitness accounts of
impact/pre-impact?  I'm particularly interested in trajectory.  This
will help determine if the unusual "sonic boom" is a related fragment.
I may have to wait for the geophysical assessment for that.

Sorry if I'm a off-topic/out of order.  I'm usually a lurker, but meteor
impacts are an interest of mine.

73, de Brad KB8UYR/6 


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