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Lightning is supposed to have killed 322 reindeer within an area that's about 50-80 meters in diameter on a mountain plateau in Norway. Nearly the entire herd died.

Sources: (1, 2, 3, 4)

enter image description here Image source

I'm struggling to comprehend how this can be possible within the laws of physics. I mean, I suppose it must be, as I'm not sure if there is any other possible explanation. But I'm asking how the idea that they were killed by lightning can be explained to be possible according to the laws of physics.

  1. How could the electricity travel between the animals? Wouldn't the reindeer have had to stand extremely close together? While the photo above does seem pretty crowded, it does also look like there would have been gaps between many of the animals. Or must they all have been touching each other directly? If not, what kind of distances are possible?

  2. Assuming that all of the 322 animals were forming a continuous chain, would the electricity from a single strike travel all the way through all of them? Or would it instead go into the ground before going all the way through that chain?

  3. Are multiple strikes of lightning a possibility? How likely is this?

  4. Could water have been involved somehow? (Apart from the water within the animals.)

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    $\begingroup$ One of the problems in my graduate comprehensive exam asked us to compute the electric potential of the ground near a lightning strike as a function of distance, and then to use that result to estimate the maximum current that could flow through the body of a person standing near the stroke. This is a non-trivial exercise, but it is worth doing. Suffice it to say that the current from the ground through a body can be non-trivial at modest distance from a stroke. $\endgroup$ – dmckee Aug 28 '16 at 21:01
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    $\begingroup$ Just speculating, if the ground is permafrost it would have high resistivity, forcing the current to flow across the surface (which is wet in summer). $\endgroup$ – Keith McClary Aug 29 '16 at 1:46
  • $\begingroup$ Your car just ran on an energized electric transmission line and the power lines all went down the road. If you touch the road anywhere within 20-30 foot near the power line in contact with the ground, you would probably get a shock.. See this: esgroundingsolutions.com/what-is-step-and-touch-potential $\endgroup$ – UKH Aug 30 '16 at 1:31
  • $\begingroup$ I'd start by asking what the required voltage would be in order to kill an adult reindeer then go from there to determine if multiple strikes were necessary. $\endgroup$ – obliv Aug 30 '16 at 1:41
  • $\begingroup$ I noticed you unaccepted my answer. Is there something you think I should fix or improve? I'm always open to suggestions. $\endgroup$ – HDE 226868 Aug 16 '17 at 20:46
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The National Weather Serivce has a page on ways someone can get struck by lightning. Two possibilities jump out at me as potential killers in the case of the reindeer:

1. Ground current

Lightning might hit a tall object - a tree, telephone pole, or something else - and travel through it into the ground. After this, it may spread out in various directions through the soil in what is termed a ground current formed by a step potential; this "kills many farm animals". In particular, quadrupeds are susceptible because their feet may be spread out quite far, and so their contact points may be quite distant, meaning that the current can travel throughout their body and vital organs. See also this page.

2. Side flashes

An object that has been struck by lightning may send current to an object close to it - resulting in a secondary strike, or a side flash. If one reindeer was struck directly, I suppose the current could then jump to a second reindeer sheltering nearby. However, 321 side flashes (there being 321 other animals to reach) is quite a lot; I don't think that this phenomenon alone could kill to many reindeer.


Gomes (2012) goes into a lot more detail, including citing specific instances. The author concludes that two cases of mass sheep deaths (654 and 850, respectively) are almost certainly due to the formation of a step potential.

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