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Science

Odd Impact Crater found in the North Sea 27

Posted by michael from the cosmic-billiards dept.
An anonymous reader writes "Just noticed this on MSNBC. It seems they discovered an impact crater in the North Sea that doesn't look like anything else seen on Earth. Supposedly it looks like something usually seen on moons of Jupiter."
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Odd Impact Crater found in the North Sea More

Odd Impact Crater found in the North Sea

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  • Earth and what's seen on Jupiter...did I miss something in the article?
    • Its the concentric circles around the crater that set this one apart from other eathly craters. They still aren't convinced that an asteroid impact could create a crater like that but may rather have been caused by "an up-from-below phenomenon known as salt diapirism."
    • ... the fact that many terrestrial impacts have only one ring, not many. It's an interesting question as to how the "extra" rings come about.

      For an example of the difference here, try dropping a decent-sized rock on a beach. The crater it creates has only the one ridge (if any). So, how do you set up those multiple rings... especially since it appears that they have approximately the same amplitudes.

      I could be wrong, but that seems to be the biggest difference... and my semi-uneducated guess is that it is most likely due to how close the impacted material is to a fluid (i.e. compare solid rock and sand), since fluids let deformation waves like these to propogate easier than solids. But, that's just a guess.

    • Multiple impacts? (Score:2, Interesting)

      by Mestophiles ( 597245 )
      Could the extra rings be caused by multiple impacts?

      • Re:Multiple impacts? (Score:2, Informative)

        by dodald ( 195775 )
        I would guess not, I am not a scientist, so this is purly a slightly educated guess.

        Inorder to gut concentric rings like that with multiple impacts I would assume that the impacts would need to be a couple of hours apart, because the initial impact would still be hot, so it would just make the crater bigger.

        Since Earth is rotating (15deg/hour) the asteroids would need to come from different directions, and the chances of that would be very high like, say 1 in 2^276709, so I would say that it was probably not multiple impacts.

        Did that make sense?

  • AP Story (Score:3, Informative)

    by ELCarlsson ( 570500 ) on Wednesday July 31, 2002 @05:40PM (#3989030)
    Here's another story about it Nandotimes.com [nandotimes.com]. I think that this is pretty neat. I'm glad to see how technology is able to detect stuff like this even deep under the sea.

  • No, that's the hard way... (Score:4, Insightful)

    by eyepeepackets ( 33477 ) on Wednesday July 31, 2002 @05:45PM (#3989052)
    ...to catch space rocks. If you let them hit the water, they splash all over everything and heat up the air. Better to catch them _before_ they enter the atmosphere.

    See, if the dinosaurs had been smarter, they wouldn't be extinct. Q.E.D.

  • Finding another impact from a metorite 65million years ago could hint at the possibility of a large solestial catastrophe that caused the end of the dinosaur era.

    Large asteroid belt collision with comet / two very very large asteroids?

    Many possible situations could lead to this... just interesting to me I guess...

  • One In A Billion (Score:3, Interesting)

    by panthro ( 552708 ) <mavrinacNO@SPAMgmail.com> on Wednesday July 31, 2002 @11:25PM (#3990260) Homepage

    Stewart said that if Silverpit was created 60 million years ago, there wouldn't be any cause to link the two impacts. "On the other hand, if it came out at 65 million years ago, we would have the possibility that Silverpit was in fact a fragment of Chicxulub [...]"

    IANAG(eologist). It seems to me, though, that if Silverpit was a fragment of Chicxulub, it would have to have hit the surface of the earth within a matter of hours as the part that hit near the Yucatan. They speak in the article of pinning the time frame down to 65 million years ago, and I'm assuming give or take half a million. With the information I have at hand, Chicxulub and Silverpit could have been up to a million years apart. Do you know what a million years is, in hours? About 8.76 billion. That's a pretty big margin of error! I don't think we should get our hopes up about the multi-dinosaur-killing-meteorites thing despite all its appeal, unless there is some other more substantial reason to believe these two meteorites had anything to do with one another. After all, a lot of meteorites hit the earth every million years.

    • It could possibly still indicate an extended period of heavy bombardment, even if the impacts were a million years apart. I imagine that's the sort of thing that gets proponents of any sort of "Nemesis" theory all hot and bothered.
    • You're right, but I think you misinterpreted what he was trying to say. He meant that if Silverpit came out to be at 65 million years, then maybe it hit within a few hours of Chicxulub. Of course, with all of this geologic dating, you're right, there is a large margin of error and we'll probably never know.

      After all, a lot of meteorites hit the earth every million years.

      Not this big they don't! A 12 mile crater! But I guess that it could be a statistical anomaly.
      • Shoemaker-Levy 9 was a comet that hit Jupiter a few years ago. Here is a link: http://www.jpl.nasa.gov/sl9/ According to the site, there were 21 discernable pieces and the collisions lasted for about 7 days. Relating Silverpit and Chicxulub wouldn't be a very large stretch of the imagination. As a side note, has anyone ever heard of, or read a study on the ages of the Moon craters?
        • No, but I have heard of some VERY interesting studies on the crater patterns on Venus. On all planets, some of the land is newer then other land, so there are more craters on the old land than the new. However, on Venus craters are perfectly evenly distributed all around the planet. This could point to there not being any new land formation, but there aren't enough craters to account for that (even after factoring in the thick atmosphere burning up meteors).

          The answer:
          Many geologists belive that there was a cataclysmic event on Venus the completely regenerated all of the land at roughly the same time, a couple of hundred million years ago. Maybe a huge asteroid impact, or maybe a natural vulcanic phenomenon.

          I'm to lazy to do a google search for you, but it's neat, huh?

  • Article lacks details (Score:2, Interesting)

    by LagDemon ( 521810 )
    I think this is a great article and all, and it raises some neat issues (maybe the catastrophe that killed the dinosaurs was a meteor storm, not just one meteor, or something), but no where in the article did it say WHY it looked like something from one of Jupiter's moons. Does anyone know why this is?

    • This article on the bbc news site [bbc.co.uk] maybe explains a little more.

      Quoting one of their paragraphs :

      "Other craters on Earth we know about were created in hard rocks, whereas Silverpit would have been formed in soft underwater sediments - creating a very different shape of crater," explains Stewart.

      This suggests that similar craters are found only in non-rocky places, such as Jupiters icy moons Callisto and Europa.

  • What *is* odd about this is... (Score:4, Informative)

    by Randym ( 25779 ) on Thursday August 01, 2002 @12:54AM (#3990477)
    ...the concentric circles. Most asteroids, because of their angle of impact, leave an elliptical footprint, with a bit of a "splash" [ejecta], sometimes forming a hill or mountain beyond the impact point. Concentric circles seem to indicate a "straight-in" impact, which leads to the idea that the object was going pretty darned fast (not slowed down much by atmosphere) *and* at just the right angle to compensate for the rotational speed of the Earth.

    Concentric circles would be more common on worlds with little atmosphere to slow the object. Since we know that Earth at that time had a (relatively) thick atmosphere, it just makes the puzzle all the more interesting. What would be interesting to find out is the metal composition at the center of the impact site -- that could tell us a great deal about what hit. Probably iron, but it *could* be something as heavy as uranium.

    • ah, but what if it was a meteor composed of iridium. or perhaps a fragment of or part of a group of iridium bearing meteors. the density of iridium is 17% higher than uranium, so it would definitely have enough energy to give the earth a good whack. maybe enough to make those interesting rings.

      the (at least partial) disintegration of such meteorites might help explain the iridium layer. perhaps the earth passed through a field of iridium bearing objects during that time. who knows. it will be interesting to see what they dig up.
    • > Concentric circles seem to indicate a
      > "straight-in" impact

      No, since the concetric circles around the crater are created by shockwaves from the impact wich propagate with the same speed in all directions through the soil - independent of the direction of the impacting object.
    • I remember seeing a study on this on Discovery or TLC. The fired rifle bullets into sand at high velocities and at many different angles, and the resulting crater was almost always circular. A quick google search turns up this link [worc.ac.uk], a section from some lecture notes at University College Worcester.

      Craters are not always circular as they may have been created from impacts which hit the surface at oblique angles forming elliptical craters however as impact craters are formed by very high velocity impacts which act essentially like an explosion rather than a distortion of the surface so unless the impact is very shallow and ploughs along the surface the craters will tend to be circular.

      Here is another interesting quote from the same page that may explain the concentric rings:

      If the crater is larger and the same order of magnitude as the thickness of the lithosphere then shock waves will penetrate the more plastic athenosphere resulting in the formation of multiringed basins.
    • Here is a link to New Scientist's [newscientist.com] coverage of the crater. They suggest that, in order to form this kind of multi-ringed crater, you need a brittle layer over a watery layer before it hits the bedrock, and that seabed sludge might have provided this structure.

  • Map URL (Score:3, Informative)

    by ke4roh ( 590577 ) <jimes@hiAUDENwaay.net minus poet> on Thursday August 01, 2002 @03:03PM (#3994552) Homepage Journal
    See a map of the crater accompanying the National Geographic story [nationalgeographic.com].

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