Airbursts, Impact Flares and Ash Falls

Mar 5, 2020
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A lot of events that produce markers for an impact are explained as asteroid airbursts. Asteroid airbursts are factual events which frequently occur.

One under reported property of airbursts is the inherent limits of their destructive power. An airburst is an asteroid which detonates before reaching the surface. The energy released by an airburst is dependent on the size, velocity, and composition of the object producing it.

An icy asteroid (comet) has low mass density and not much structural strength. Even with these limitations an icy asteroid can still impact if it is large enough or if it is moving fast enough. This would tend to limit the explosive yield of an airburst to (a guess) 5 to 10 megatons before it will always produce a surface crater.

For denser or stronger masses like rock and iron these numbers go down since these masses have a greater chance of reaching the ground and producing a visible crater. Airbursts therefore have upper limits on the energy that they can release before they will produce an impact crater.

If someone puts forth a scenario where a vast area >10,000 km^2 is affected by an airburst then they have blamed the wrong phenomenon.

The flare of energy (thermal energy released by a column of vaporized rock) produced by an interstellar impact is capable of affecting an area > 1,000,000 km^2. These impacts can leave behind flood basalts and impact structures which superficially resemble volcanic structures.

One of the features which can help determine whether an airburst is responsible for the damage in a particular area is the presence of an ash layer. Since the body which produced the airburst never reached the ground it can only produce a limited amount of ash. That ash would be the disintegrated mass of the asteroid along with any ash produced by surface fires such as forests. The chemistry of the ash would look like powdered asteroid mixed with organic ash.

In the case of an interstellar (or high velocity) impact the amount of ash located near the impact point could be much greater than 10 cm. The Impact point itself might be barren of ash since the outflow from the flare might blast it away. At some distance from the impact point a significant ash layer will be deposited. The chemistry of an interstellar impact ash layer is dependent upon the energy of the impact.

(breaking this up into bite size pieces to compensate for my attention span)​
 
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Very high energy interstellar impact’s produce massive extinctions and the worldwide development of black shale and oil deposits. These are not anoxia events. In any case no one blames major extinction events on airbursts.

However, a recent extinction event coincident with the Impact(s) at the Younger Dryas (YD) are blamed on airbursts. One potential impact site the John Tuzo Wilson seamount off of the western coast of Canada has glauconite deposited on the surface of the sediments surrounding it. Since it is so deep under water only the high energy products produced by the impact flare would be able to blast clear of the water. The appearance of glauconite without any ash would therefore be diagnostic of a water impact.

The YD glauconite may have made it to the Clovis sites. Other bodies of water on the North American continent at the time of the impact may contain a distinct layer of glauconite. My searches on the subject returned a lot of evasive answers. Since the YD event was only 13000 years ago a hand corer might be sufficient to recover this marker in lake or paleolake sediments near the JTW impact site.

At sites like the Bonneville salt flats and the Great Salt Lake it might require more dedicated equipment to sample this marker (if it is present at this distance from the impact).

I was doing some research related to the digs at Tall el-Hammam which are suspected to be the ruins of the biblical city of Sodom. Objects at the site had thermal damage consistent with an airburst event. Welded rock (scoria like objects) and even pottery glazed by a very high but rapid thermal pulse. The only potential discrepancy was a 20 cm layer of ash.

I have been unable to find a chemical analysis for that ash. While searching for information about a tephra layer in that region I came across something called the Khabur Tephra. That led me to Syria and the impacts which directly affected human history by destroying the Akkadian Empire.

I also realized that ash could be a diagnostic marker for different kinds of impacts.

An ordinary airburst will produce little to no ash (other than fires).

A smaller interstellar impact would produce either limited or no glauconite with substantial ash.

A (larger) interstellar impact into deep water would only produce glauconite at land sites since deep water would suppress ash ejection into the atmosphere.

A (larger) interstellar impact onto dry land could produce a base layer of glauconite buried by ash.

The impact and any ash layer would tell you a lot about whether it was an airburst, an interstellar impact into the ocean, or an interstellar impact on dry land.
 
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If you want to find out if there were any other interruptions to human civilizations in the Mediterranean you need to look for ash and tephra layers. The Santorini mega-super-explosion barely blew material more than 100 kilometers. The Santorini seismic and tidal waves that supposedly destroyed the eastern Mediterranean may not have happened at all.

The Empire went to a lot of trouble to hide something around Israel or Egypt. If they went to this much trouble then there are obvious ash and tephra markers in this area. Don’t buy the fake Santorini story as the origin for these ash layers. They also like to blame volcanoes in Turkey so that origin is likely fake for the tephra and ash in the Levant.

How about measuring the sediments off of the Israeli coast and looking for ash? These markers could be less than 2 meters from the top of the sediments. How about looking at the sediments on the bottom of Lake Galilee? Or sediments in the Dead Sea? Some of the salt pans and dried up lakes might also work.

The Akkadian impact apparently caused a major rainstorm, kind of gluing the marker in place. If the ash fell into a salt pan or lake the rain might dissolve the salt sealing in the ash and keeping it from blowing away. In the right place all you might need is a shovel to find the markers.

Science can be a lot of fun when you ruin a fake scientist’s career. You are Indiana Jones and they are the bad guys.
 

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