Ancient Crash, Epic Wave

avtchillsboro writes "A NY Times article says that scientists have discovered evidence a massive impact crater 18 miles in diameter and 12,500 feet under the Indian Ocean. The evidence, they say, consists of four massive chevron-shaped sediment deposits on the island of Madagascar. '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.' Interestingly, the scientists say that the currently accepted notion that there have been no major impacts in the last 10,000 years is wrong; and that major impacts occur on average every 1,000 years, rather than the currently accepted 500,000 to 1,000,000 year interval. '(T)he self-described "band of misfits" that make up the two-year-old Holocene Impact Working Group say that astronomers simply have not known how or where to look for evidence of such impacts along the world's shorelines and in the deep ocean.'"

Re:

[Knuckles]

Hi Mipoti, when you were banned you wrote this posting [slashdot.org] as an Anonymous Coward. I answered you here [slashdot.org] but then I realized you might not see it there, and so I write this reply to a posting you made under your nickname in the hope that you will see it.

Does this mean primitive life on earth started out

[Timesprout]

as Surfer Dudes? We may finally be able to shed some light on kowabunga now.

spookee

[Hognoxious]

Having just read "Footfall", I for one welcome our new double-trunked pachyderm overlords.

Re:

[miller701]

Having just read "Footfall", I for one welcome our new double-trunked pachyderm overlords.

Didn't they just get voted out of office?

Ancient crash?

[LiquidCoooled]

Does that mean Microsoft was behind the blue wave of death?

Re:

[r_jensen11]

Either them or NASA

No games?

[sexyrexy]

When I read the title, I thought it was about Epic and a studio called Ancient that tanked.

I thought it sounded familiar

[smooth wombat]

And then I realized, it's from 6 days ago when I posted the exact same story in my journal [slashdot.org]. On top of which I had also checked it off to be a possible story and the editors of course rejected it.

Slashdot, where the news is stale, the editors don't edit and geeks still can't get a girlfriend.

Ooops you went too far.

[tgd]

Insulting Slashdot is a good way to get modded up, but pointing out the lack of girlfriends is going to swing the moderators the other direction!

N00b mistake...

You always comment on the staleness of news, then insult Zonk, make a side quip about dupes and leave the girlfriend angle out.

Thats the secret to high karma!

Re:

[barakn]

Perhaps they didn't like the fact that your journal entry said "no reg required" when, in fact, registration is required.

Interesting methods, troubling results

[zeropointburn]

This is somewhat troubling. Before these people went looking, we assumed we had somewhere between now and 10,000 AD or so before the next major impact. (mangling the fine art of statistics, I know) Now, they're saying it could be a thousand years or less between impacts. When was the last major impact? We could be due for a serious catastrophe in very short order, practically instantaneous in geological terms.
I'm certainly not reassured by the fact that we only monitor about 3% of the sky. Sure, we think we know about every significant object that approaches Earth, but that doesn't account for rogue objects (those with either highly elliptical or hyperbolic orbits, or extrasolar objects that can't currently be tracked or predicted). Since FEMA is basically shite and lunar exploration/colonization is basically all hype at this point, what the hell are we going to do if we find out tomorrow that the world as we know it will shortly end?

Tinfoil hats aside, there's some excellent insight into scanning technology presented in the article. The idea of precisely scanning sea surface height to identify local gravitational variations interests me greatly. Just think about that for a little bit; let the sheer coolness of such remarkable precision sink in. It's also interesting to note that miles-wide craters have escaped our notice for millenia. Props for taking the obvious route and playing connect-the-dots with geological formations.
Of course, the doubt is strong already amongst the established scientific community. I'd say that since they've already done sediment tests for several sites and identified tektites neatly fused with diatoms (meteor debris melted to fossil plants), it's pretty clear that their methods are valid and are producing reliable results.
The note at the end of TFA about using Flood myths to date and place a major impact is particularly intriguing. Some of the 'researchers' that have taken the route of aggregate myth analysis have come up with some pretty questionable results, but in other cases, surprising correlations stand out. Consider that virtually every culture, living or dead, has a flood myth in some form or another. I think it's good for us all to be reminded that myths and legends are based on real people and events, however obsured by the ravages of time and creative retelling.
That's all I've got...

Re:Interesting methods, troubling results

[Dunbal]

what the hell are we going to do if we find out tomorrow that the world as we know it will shortly end?

Die?

Consider that virtually every culture, living or dead, has a flood myth in some form or another. I think it's good for us all to be reminded that myths and legends are based on real people and events, however obsured by the ravages of time and creative retelling.

      Since human life is pretty strongly interrelated with water, and most of our communities have to be near water (with few exceptions), it's not surprising that there are flood myths. The source of these myths don't have to be global catastrophes however. Just the occasional river flood, or storm, could be enough to reinforce the idea of flooding as something bad. Then some creative soul exaggerates "that flood we had 20 years ago" and the flood myth is born.

      Remember if we're talking huge tidal waves from a large meteor impact, the people who witness this wave (albeit briefly) are quite unlikely to survive long enough to tell others about it.

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[zeropointburn]

Remember if we're talking huge tidal waves from a large meteor impact, the people who witness this wave (albeit briefly) are quite unlikely to survive long enough to tell others about it.
Yes and no... There are places where mountain chains run right into the ocean, for starters. A few people could have survived. Besides, people who lived far enough away from shore, or high enough to avoid the surge, would have been able to see the devastation long after the event. If you were to go to New Orleans today, y

Re:

[khallow]

As for dying, should a large impact occur, you're exactly right. We'll be dying by the billions. All the preparation in the world would be meaningless if a hefty chunk of rock were to impact anywhere near you at a few kilometers per second. The only realistic means of preserving humanity in such an event would be successfully, sustainably establishing a permanent human presence in space before it all went down. Not a few people in a space station, but thousands or more wherever we can make it work. For tho

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[zeropointburn]

I stand corrected.
You're absolutely right: a 10-megaton impact would be quite surviveable for the majority of humans. Certainly locally catastrophic, but bomb shelters and the like would be useful down to some distance from impact (based on size, density, velocity, and material at impact, as well as shelter design). I did specify 'large impact', but it was in the context of the article, so that would equate to about 10 megatons.
This would help explain how they came up with the 1,000 year per impact number

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[khallow]

One thing that bothers me here is that the impact site is supposed to be 900 miles away (if I read the article correctly). So 10 megatons seems very small to have caused the chevrons at that distance. This might just be an indication that the impact was a glancing blow (which apparently are fairly common) with the energy (and most of the debris) focused on the southern shore of Madagascar.

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[Noxx]

I think most people are less concerned with {civilization | species | all life} -ending disasters than they are with convenience-ending disasters.

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[khallow]

OTOH, a convenience-ending disaster taking place during a time of high international tension might spark a civilization-ending war.

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[Impy the Impiuos Imp]

> Yes and no... There are places where mountain chains run right into the ocean, for starters. A few people could have survived.

Yes, but we have, sadly, a recent data point with the recent tsunami. Of the dozens of films, none come from areas where the waves were 20 feet or higher, so we don't know what it was like in the worst areas. You'd have to get lucky with that or someone on a pole with a camera by pure coincidence. Most areas will just be flattened, including modern buildings. If it's a metro

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[Dunbal]

Of the dozens of films, none come from areas where the waves were 20 feet or higher,

Don't think of a tsunami as a traditional wave - it's not. It's a wave with an EXTREMELY long wavelength, in the km range. So from your perspective it will just look like the ocean decides to come inland. The water level rises suddenly, and keeps rising. Don't look for a "crest", there won't be one. Just water coming inland constantly, and knocking everything down. Then the "wave" recedes, because once

Don't look for a "crest"

[fuego451]

I'm not disputing anything you say but the tsunami video which, I believe, was taken in Banda Ache, with pool below and sea wall beyond at the beach edge, shows a beautifully formed 'wave' which crests and breaks in a very surfable form, for a few seconds. I believe this happened at this particular beach because of a very steep drop-off to deep water. Another video taken at a beach with a very gradual slope, I can't remember where, shows a 5-6 foot mass of water coming in with churning whitewater at its fro

Re:

[Marxist Hacker 42]

I'm willing to bet the Nehalem Native Americans would survive such a thing. They have a habit of running up Neahkahnie Mountain when the ocean receeds greatly- and unless such a mega-tsunami could top 2000 feet, at least some would survive to tell the tale. Of course, they get big floods every winter, so it's not such a big deal....

Re:

[Impy the Impiuos Imp]

what the hell are we going to do if we find out tomorrow that the world as we know it will shortly end?

Die?

"I'm a nerd and have never known the touch of a woman. I don't want to die without having sampled the sweet mystery of life. Can you help me?"

Pick a response:

A. "Uhhh, I promised myself to some guy down the hall, bye."

B. "I'd love to, but I don't want to die knowing unbathed teen males from the Warhammer room in the back of the hobby shop."

C. "No, I love you, but I'm your mother and that's just gros

Re:

[iogan]

The note at the end of TFA about using Flood myths to date and place a major impact is particularly intriguing. Some of the 'researchers' that have taken the route of aggregate myth analysis have come up with some pretty questionable results, but in other cases, surprising correlations stand out. Consider that virtually every culture, living or dead, has a flood myth in some form or another. I think it's good for us all to be reminded that myths and legends are based on real people and events, however obsur

Re:

[zeropointburn]

Zecharia Sitchin has some interesting things to say about this very subject. I don't agree with everything he concludes, but the evidence he's dug up is most intriguing.
To be honest, I don't have a definite opinion on the subject of alien visitations. I haven't seen any solid evidence with my own eyes, but I've also never seen any counterevidence. On a theoretical basis, the thought that this is the only inhabited planet in the universe is a flat impossibility.
As for the fundies, denying scientific eviden

Re:

[infolib]

that doesn't account for rogue objects (those with either highly elliptical or hyperbolic orbits

If it has a hyperbolic orbit it's from outside the solar system. Not from "beyond Plu^W^W^W Neptune" but from interstellar space and on its way out again. AFAIK we haven't spotted any such objects yet (apart from cosmic radiation) and if we do, I'd almost hope it impacts just so we can get our hands on the samples.

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[khallow]

Since FEMA is basically shite

This is incorrect. Despite the blamefinding afterwards, Hurricane Katrina is an excellent counterexample. And there has been no other such incident in which FEMA's competence was questioned.

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[Impy the Impiuos Imp]

> When was the last major impact?

The moon, a much smaller body, had one only a few centuries ago, visible to much of the world and well-recorded. Jupiter, much larger, had one just a few years ago. Then there was the Tunguska event.

So even allowing for much larger and multiple heavenly bodies, which might bring the rate up to 1/100,000 years cumulatively, well, 3 data points is enough to suggest it's statistically a hell of a lot more frequent than once every 100,000 years.

More common than we thought.

[KwKSilver]

They do seem to be more common than we, at at least I, thought. I was surprised to learn earlier this year that an old friend of mine and his colleagues from the Louisiana geological survey had found evidence of a possible impact crater two kilometers across about 52 km northeast of Baton Rouge, Louisiana. See here [searchanddiscovery.net]. That's fairly close & fairly recent, too, as it seems to be Late Pleistocene and possibly as recent as 11 thousand years ago.

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[cs]

Now, they're saying it could be a thousand years or less between impacts. When was the last major impact? We could be due for a serious catastrophe in very short order, practically instantaneous in geological terms.

It doesn't matter when the last impact was. The greater frequency does imply the risk of such an impact soon is correspondingly higher, but unless there is some clockwork mechanism directing impactors at us regularly, the time since the last impact has NO bearing on the likely time to another.

Re:

[zeropointburn]

I should have been more precise. I did admit to mangling the fine art of statistics, though. In proper terms, this means that instead of a 1/100,000 chance of an impact next year, it might actually be 1/1,000. Such a dramatic change in a value we once held to be pretty accurate is jarring, particularly given the subject matter.
As stated previously by others, though, this survey is turning up smaller impacts than we typically see on land. Probably, this is because erosion on land erases craters of this size

New SI units

[Dunbal]

Each covers twice the area of Manhattan with sediment as deep as the Chrysler Building is high.

      Can anyone help me with the conversion here? How many football fields to a Chrysler Building, and how many cubic libraries of congress to a Manhattan? Sheesh whatever happened to things like meters, or even feet?

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[mrjb]

Turns out it is 1.58573928 furlongs high.

Re:

[sho-gun]

You forgot the most popular unit of comparison: VW Bugs!

Re:

[RingDev]

Is that in new bugs or old bugs?

-Rick

Re:

[Red Flayer]

How many football fields to a Chrysler Building

With or without the endzones?

how many cubic libraries of congress to a Manhattan?

Huh? That's just apples and oranges, my friend. LoCs are a measurement of data capacity, not physical volume. Besides, the "area of Manhattan" is two-dimensional, not a cubic measurement.

It's all well and good to ask for measurements in standard units like an LoC, but let's make sure we use them correctly.

The correct answer would be 3.487 football fields (sans endzones) high

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[Red Flayer]

Not sure of you're trying to be funny or not... but populations has nothing to do with the calculation. A hogshead is a unit of volume, based on a cylindrical container roughly 18" diameter by 30" l.

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[Tet]

The correct answer would be 3.487 football fields (sans endzones) high over two Manhattans, or 8,086,748.43 hogsheads. Was that so hard?

Actually, yes. How tall is the Chrysler building? Do you measure to the highest floor? The roof? The top of the antenna? Then you get into how long is a football field? To most of the world's population, it's typically 105m. But it may be between around 90 and 120m (excluding those variants which allow for an infinitely sized pitch). So the Chrysler:Football field ratio c

Written history

[Dan East]

This happened only 4,800 years ago. The impact would have had global repercussions, so shouldn't it be reflected in written history, like in Egypt?

Dan East

Re:

[Anonymous Coward]

4,800 years ago would be Pre-dynastic Eygpt, so it'd be better looking elsewhere, maybe mesopotamia?

Re:

[kalidasa]

4,800 bp is ~2800 bc. -- Second Dynasty, I think, not pre-dynastic. It would be predynastic in China and during the chaotic early period of Mesopotamia (don't remember the technical names for either). Not much in the way of useful records, at any rate.

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[lawpoop]

Try China.

Re:Written history

[dreamchaser]

You mean like the Great Flood stories shared by most ancient civilizations?

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[Lucky_Norseman]

Or like the crossing of the Red Sea. Where the water first pulled back and then a short while later came crashing down with devastating force. Just like the Tsunami two years ago.

santorini

[slashmojo]

Or like the crossing of the Red Sea. Where the water first pulled back and then a short while later came crashing down with devastating force.

The volcano eruption on the greek island of santorini has been suggested as a possible cause of that (and related) biblical event.

http://www.telegraph.co.uk/.. [telegraph.co.uk]

How deep?

[mrjb]

"with sediment as deep as the Chrysler Building is high" Sorry- can someone convert that to furlongs?

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[Reziac]

Furlongs is a measure of distance. You want fathoms, a measure of depth.

Re:

[Bloke down the pub]

Just multiply by -110i

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[Reziac]

Multiply?! what sort of math are they teaching these days? Everyone knows you're supposed to *divide* by -110i, then take the square root of the remainder!

See it in context thanks to Google Maps

[Anonymous Coward]

If you're interested in looking at the Google Earth view of the features mentioned in the article, look here [google.com].

Be sure to look up and down the coast on either side of this particular feature.

Re:

[dwater]

Looks like Google *Maps* to me....which would be cool if there was a link to the crater they're talking about....

Lots of water

[CmdrGravy]

I'm surprised these people seem to be the first to start looking for impact craters in the Ocean, being as it covers 3/4 of the globe it stands to reason that 3/4 of all impacts are going to end up in the Ocean somewhere. Maybe it's just a case of only having the necessary technology available fairly recently but I think we ought to be doing everything we can to understand how often and how much damage asteroid strikes occur and can inflict.

Also the size of the Tsunami which created those chevrons must have been almost unimaginably huge but again its likely that for every impact of that size there would have been a lot more which haven't left such obvious signs but would still have been capable of inflicting similar destruction on coastal communities as the Indonesian Tsunami did a few years ago.

Although I think traditional science is a better method of investigating these sorts of incidents I think the idea of tracing back through myths and stories to reach an actual point in time where some group of people actually experienced the event is fascinating. Whether it's just wishful thinking or not and can ever be tied down this precisely is I think questionable.

Any event which caused waves of that size is pretty clearly going to make a big impression on anyone who witnessed any of its effects and would certainly have been talked about for a very long time but whether we can detect any of the story as it must have been originally told is, in my opinion, extremely unlikely.

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[Remus Shepherd]

Most researchers never bothered looking for deep ocean impact craters because they assumed the craters would be covered in sediment. In fact, they probably *are* covered in sediment, and it's only because of the new gravimetric technology that we can see them at all.

Another picture of the chevrons is here. [usgs.gov] Features like this are visible all over the world, as the graphic accompanying the NYT article shows. Pretty spooky...I just never realized before how much scar tissue the Earth has on her.

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[radtea]

Although I think traditional science is a better method of investigating these sorts of incidents I think the idea of tracing back through myths and stories to reach an actual point in time where some group of people actually experienced the event is fascinating. Whether it's just wishful thinking or not and can ever be tied down this precisely is I think questionable.

This article [pnsn.org] gives an idea of how difficult it is to tie down anything specific from myth and oral history, at least in part due to the very

Re:

[Bloke down the pub]

It would be amusing if the Sumerian flood story, frequently assumed to be the source of the Biblical flood story, in its own turn was found to be derivative of a quite different story from far away.

I'm sure that intellectual propeerty lawyers are comparing them as we speak.

Re:

[khallow]

First, those craters are covered by water and (as another replier pointed out) sediment. Second, the ocean crust tends to be a lot newer than continental crust since it is routinely subducted and destroyed. There's no three billion year old ocean crust out there.

Re:

[barakn]

Oceanic crust recycles itself much faster than continental crust. You'd have a hard if not impossible time [noaa.gov] finding ocean crust older than 200 million years, but there are areas of continents [lithosphere.info] over 3 billion years old. Thus one should expect to find less than 3/4 of all impacts in the oceans.

You can check out the chevrons on Google Maps

[bestinshow]

They're at the south end of Madagascar. Worth a look, in fact at first glance a lot of the south-eastern coast looks like it is showing signs of where a tsunami washed inland a lot, but the chevrons are very clear when you find them. Also there appear to be some more chevrons at the top end of the country, at a different angle, but it's not my line of expertise so I may be wrong.

However it is a neat method of finding recent oceanic meteorite impacts. I don't know how long the chevrons would last - the bigger the impact the longer they'd last seems like an obvious insight though, and 600ft high chevrons would take a very long time to erode, ice ages notwithstanding.

Interesting research, but ...

[Mostly a lurker]

... I find it difficult to understand how failure to account before for ocean impacts of meteors could change the anticipated frequency of large meteor impacts from once every 500,000-1,000,000 years to once every 1,000. Surely, a frequency of once every 1,000 years or so would mean several hundred hitting land every million years. Those would, one imagines, leave pretty obvious evidence.

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[meglon]

Time has a good way of eliminating "pretty obvious" marks. Consider the Iturralde Crater is probably no more than 30k years old, at the outside.. it was only found by satellite photographs. Consider Angkor Wat, Aztec city of Yautepec, Machu Picchu. All of these were basically lost in a fairly short time (geologically) due to the elements and nature. Although man-made, they were certainly pretty big marks on the area around them.

That's assuming impacts. If they broke up in the air, then the traces wo

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[Bandman]

what is this "blast in the Egyptian desert" you speak of?

Re:

[meglon]

http://news.bbc.co.uk/2/hi/science/nature/5196362. stm [bbc.co.uk]

If you get a chance to catch a re-run of the program, it's pretty well done.

Re:

[salec]

Well if asteroid falls in the forest ... never mind that, I mean: before we had Earth covered with radio stations, and before we sailed high seas on regular basis, many a catastrophy could had pass unnoticed in "mainstream cultural thread". Westerners tend to dismiss other people's oral traditions as fantastic gibberish. Now, that time frame, from Columbus and Magellan till today is less than 1000 years.

Chevrons?

[inviolet]

There are Chevrons all over the place here in Houston... practically on every street corner. And there's one really big one downtown, possibly indicating the epicenter of a larger impact.

Other Shaped Impacts Are Now Being Investigated

[LifesABeach]

For some bored silly reason, I am waiting for the following NY Times story to be posted:
(New York) - Exxon, and Shell Oil not to be out marketed by Chevron have begun evaluation of other possible impact sites for shapes that would look like their corporate logos.

Drop the historic units!

[gweihir]

All this "mile", "feet" and so nonsense, like if we were in primitive company here. Drop the historic stuff and use scientific units (i.e. metric) already! That some countries ara backwards in this regard, should not hinder Shlashdot!

Libraries of congress

[alexhard]

Each covers twice the area of Manhattan with sediment as deep as the Chrysler Building is high.

Yeah, but how many libraries of congress is it in volume?

Re:

[zeropointburn]

Manhattan's area is about 60 km. The Chrysler building is 0.319 km tall. The volume in question is thus 120km * 0.319km = 38.28km.
Estimates on the volume of the Library of Congress vary, partly because it is housed in three separate buildings, and floor plans aren't immediately available, nor are values for area or volume. This answer will use the listed shelf space as a least-volume indicator, assuming the shelves are 3 meters high and 1 meter deep. This is totally arbitrary, but should give a rough esti

Re:

[zeropointburn]

OK, so the square and cube symbols didn't transfer, for some reason. Here it is again in caret notation.

2 * area of manhattan = 120 km^2 * height of chrysler building (0.319 km) = 38.28 km^3
.001 km * .003 km * 850 km = .0255 km^3, rounded to 0.03 km^3 to account for non-shelving space.
Thus, the area in question, 38.28 km^3 = 1,276 cLoC.
Apologies for the mistake; it previewed correctly :(

Re:

[alexhard]

wow. O_O

Catastrophism

[buckethead]

Maybe Velikovsky was right...

Tsunami "expert" Ted Bryant

[Spalti]

After RTFA, I found out Ted Bryant is the Tsunami expert in this group of researchers. While researching for my thesis, I was confronted with his book, "Tsunami: the underrated hazard". This work, while being quite easy to understand, can hardly be called scientific based on his way of making citations (grouping all references at the beginning of a chapter which leaves you without the possibility to look up where he drew his conclusions from).

Reviews of his book can be found here: http://hol.sagepub.com/cgi/reprint/12/5/637 [sagepub.com] and here http://dx.doi.org/10.1016/S0025-3227(03)00086-0 [doi.org] and here: Synolakis, C.E., and G.J. Fryer, 2001. Book Review: Tsunami: the underrated hazard by Edward Bryant, Eos, Trans. Am. Geophys. Union, 82, 588 (can't find a quick link right now).

The existence of so-called megatsunamis is hardly scientifically proven, especially not by the work of Bryant (he classified sedimentary features embedded in sandstone somewhere in Australia as relics of an ancient megatsunami when in a nearby graveyard the same sandstone wouldn't resist local climate and erosion for more than a few centuries).

The propagation of tsunamis with huge waveheights seems to be limited due to dispersion effects and the so-called "Van-Dorn-Effect" should cause these huge waves to break as soon as they reach the continental shelf (http://www.agu.org/pubs/crossref/2005/2004GL02191 8.shtml [agu.org] and http://www.lpl.arizona.edu/~jmelosh/ImpactTsunami. pdf [arizona.edu] , but also http://www.spaceref.com/news/viewpr.html?pid=10986 [spaceref.com]).

After working some time in the field of megatsunamis (my thesis concentrated on the Cumbre Vieja Scenario postulated by Ward&Day back in 2001 (http://www.es.ucsc.edu/~ward/papers/La_Palma_grl. pdf [ucsc.edu]) and, based on scientific grounds, I had to "debunk" it as several researchers have done before me), I have learned to take these reports with a grain (or better, a big portion) of salt.