Did an Asteroid Impact Cause an Ancient Tsunami?

NYT ^ | Nov 14 2006 | SANDRA BLAKESLEE

[djf]

At the southern end of Madagascar lie four enormous wedge-shaped sediment deposits, called chevrons, that are composed of material from the ocean floor. Each covers twice the area of Manhattan with sediment as deep as the Chrysler Building is high.

On close inspection, the chevron deposits contain deep ocean microfossils that are fused with a medley of metals typically formed by cosmic impacts. And all of them point in the same direction — toward the middle of the Indian Ocean where a newly discovered crater, 18 miles in diameter, lies 12,500 feet below the surface.

The explanation is obvious to some scientists. A large asteroid or comet, the kind that could kill a quarter of the world’s population, smashed into the Indian Ocean 4,800 years ago, producing a tsunami at least 600 feet high, about 13 times as big as the one that inundated Indonesia nearly two years ago. The wave carried the huge deposits of sediment to land.

[djf]

When I get back online to my high-speed, I'm gonna try to get some satellite images.

[Sen Jack S. Fogbound]

4,800 years ago? Hmmm, that might explain why much of our "civilized" world started by then.

There are reports of previous civilizations older than 6,000 years ago. Such as one city of at least 10,000 years or better ago.

Race memory?

[djf]

Thing is, this isn't like having an 18 mile wide crater on the surface, which by itself would have been a catastrophe beyond description.

This is an 18 mile wide crater AFTER IT HAD TRAVELLED THROUGH 2 MILES OF OCEAN!!

I remember reading something about it raining forty days and forty nights, this sure would do it.

[nitzy]

Bush's fault

[edcoil]

Egypt caused Global Warming - or God did. Take your choice.

[Interesting Times]

Ping.

[lafroste]

Interesting article. It implies that catastrophic cosmic strikes are more frequent than we currently believe. Question: How large of an asteroid is needed to make an 18 mile diameter crater (under 12,500 feet of water)? Anyone know?

[GOPJ]

the Earth suffers a violent impact on the order of a 10-megaton explosion. Instead of once in 500,000 to one million years, as astronomers now calculate, catastrophic impacts could happen every few thousand years.

Well, don't have to spend a lot of time worrying about global warming...

[djf]

Dunno. But after thinking about it, there would be a huge pneumatic effect. Liquid does, after all, in a case like this practically act like a solid. A unbelievable compression wave would travel almost immediately to the ocean floor. Like God had a giant toilet plunger. I'm talking a really, really,really BIG toilet plunger.

Trillions of tons of seawater would be instantly evaporated. I would think they should look for salt layers in the area.

[Blue Jays]

It would be interesting to see a modern artist's interpretation of what that wave must have looked like in the final devastating moments. The roar alone must have been deafening...plus something that tall must have created an enormous wind that preceded it.

[DBrow]

4800 years?

[null and void]

Ancient Crash, Epic Wave

[Mad Dawg]

How large of an asteroid is needed to make an 18 mile diameter crater (under 12,500 feet of water)? Anyone know?

I would say somewhere between "big mother" and "homper-stomper". Of course, a more careful examination of the data might increase the estimate to "Some KIND of homper-stomper, I tell you WHAT" but we'll just have to wait for more information.

[blam]

Ancient Crash, Epic Wave

[null and void]

beat ya!

[djf]

Did a search on "ancient", didn't see it...

[blam]

"There are reports of previous civilizations older than 6,000 years ago. Such as one city of at least 10,000 years or better ago."

Lost Civilisation From 7,500 BC Discovered Off Indian Coast

[null and void]

Yeah. The search function doesn't always work very well.

[blam]

"Did a search on "ancient", didn't see it..."

The more the merrier...I say.