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Siberia was formed as a result of a massive hotspot volcano (Siberian Traps) ~250 million years ago (mya) and so was India ~64 mya (Deccan Traps).

So, I was working on a random planet generator for hobby video game and I was working out some basic magnetohydrodynamics and stuff and I started thinking about the causes of these big eruptions . . .

And then I remember in both instances, there are major extinction events attributed to these events. In the case of India, I remember hearing a debate about the causes of dinosaur extinction being a meteor impact in the Yucatan and/or the eruption which formed India.

So I was thinking that an impact of sufficient magnitude could cause a shock wave through the mantle. Such a shock wave would traverse the mantle (in geometry such a manifold is called a 2-sphere) and re-converge on the opposite side of the planet (antipodes).

My question concerns such events. Couldn't the compression of a wave traveling through the mantle cause the magma to 'align' magnetically?

If so, could this trigger the flow of material to follow the wave form? And, because the shock wave would traverse the 2-sphere, it would be forced to converge at an antipodal point and, could this convergence possibly drive the formation of hotspots?

I ask because India is (or was) awfully close to the opposite side of the Earth as the Yucatan.

Further, I remember when studying the surface of Mars, a similar correlation between Hellas Planitia and Olympus Mons.

Is there such an associated crater with the Siberian Traps?

And is there any sort of research going on about this phenomena?

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  • $\begingroup$ Given that Siberia was formed as a result of a massive hotspot volcano ~250 mya and so was india (~64 mya). I need sources for those both. Neither sounds correct. The latter is absolutely wrong, at least in date. $\endgroup$
    – HDE 226868 ♦
    Jun 30, 2015 at 22:00
  • $\begingroup$ en.wikipedia.org/wiki/Siberian_Traps $\endgroup$
    – punkerplunk
    Jun 30, 2015 at 22:07
  • $\begingroup$ They didn't form Siberia, though. $\endgroup$
    – HDE 226868 ♦
    Jun 30, 2015 at 22:07
  • $\begingroup$ en.wikipedia.org/wiki/Deccan_Traps $\endgroup$
    – punkerplunk
    Jun 30, 2015 at 22:07
  • $\begingroup$ Same for the Deccan traps. I'm not splitting hairs. I'm correcting an incorrect assertion you made that seems central to your question. Also, did you read why the Deccan trap might have influenced the dinosaur extinction? It was gas release, not some giant eruption. You've misunderstood it. $\endgroup$
    – HDE 226868 ♦
    Jun 30, 2015 at 22:08

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While it sounds reasonable in principle (I had this thought myself), the convergence of the shockwaves on the far side of the sphere is not going to cause the effect they way you are describing.

The shockwaves will probably cause earthquakes and may even trigger existing volcanic hotspots (assuming there are any nearby), but the Earth's mantle is made of silicate rock, rather than metals. The Earth's iron mostly flowed to the liquid outer core and solid inner core aeons ago as the Earth grew and heated up, leaving only a relatively small amount sprinked everywhere else (relative to the size of the core, that is).

Since the magnetic field is generated by the rotating liquid outer core, the shock waves do have the potential to destabilize the field, perhaps triggering a magnetic field reversal (although I'm not clear if such an event happened during the mega eruptions you are referencing). Otherwise, the physical shockwaves will pass through the silicate rock of the mantle, converge on the far side and potentially cause enough stress on the solid lithosphere to trigger earthquakes and volcanic eruptions.

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Very large meteor impacts appear to have some of the effects that you ascribe to them. Notably, the Colaris Basin on Mercury appears to be an impact crater by an object 100+ miles in diameter.

The Antipodes of Mercury from this impact display disrupted terrain in the manner reminiscent of your description.

1300 km Caloris Basin
1300 km Caloris Basin

At the exact antipode of the basin is a large area of hilly, grooved terrain, with few small impact craters that are known as the Chaotic Terrain (also "Weird Terrain"). It is thought by some to have been created as seismic waves from the impact converged on the opposite side of the planet.[6] Alternatively, it has been suggested that this terrain formed as a result of the convergence of ejecta at this basin’s antipode.[7] This hypothetical impact is also believed to have triggered volcanic activity on Mercury, resulting in the formation of smooth plains.[8] Surrounding Caloris Basin is a series of geologic formations thought to have been produced by the basin's ejecta, collectively called the Caloris Group.

Antipodes Chaotic Terrain
Antipodes Chaotic Terrain

Despite the accurate description of the seismic effects of large impacts, I doubt that such an impact would cause the mantle to "magnetically align". On the other hand, you are writing fiction and can state that this happens if it is crucial to your story.

Are you looking for a semi-plausible mechanism for this to happen?

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  • $\begingroup$ The characters are 'world builders' and I need methods for them to shape tectonics OTHER than a magic, mysterious floating cursor. The thought is they could set something in motion and then fly away at near speed of light and return millions of relative years later (as the simulator bakes) to observe the results. So I'd like something plausible, which begs another question: What methods ARE available to manipulate tectonics? $\endgroup$
    – punkerplunk
    Jul 1, 2015 at 10:02
  • $\begingroup$ Planetary tectonics are driven by two main factors: heat production and dissipation. Heat production from planetary formation + decay of radioactive elements. Heat dissipation by radiation to space. If you want more volcanic activity, then you need more heat. Add heat by introducing (huge quantities) of radioactive elements where you want the volcano. $\endgroup$
    – Jim2B
    Jul 1, 2015 at 14:42
  • $\begingroup$ The difference between how Earth and Venus volcanic activity may be the presence of water. Which begs the question, was Venus more Earth like before it lost its water? I don't know. $\endgroup$
    – Jim2B
    Jul 1, 2015 at 14:44

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