Re: tsunami impact on animals

Don Nield wrote:

"...Incidentally, I read somewhere of a report from East Africa (I think)
that some hippopotami were swept out to sea. It is understandable that
because they were in a river they would not have picked up the seismic
vibrations that are restricted to dry land."

There might be several reasons why hippopotami might not seek high ground when other animals would. But the river bottom would have vibrated much like dry land. The animals might not have sensed it if they were swimming, even though the water also would have transmitted the seismic energy. (Much oil industry seismic recording is done with receivers suspended in water.)

However, east Africa is much farther from the earthquake focus than Sri Lanka, so the seismic displacements would have been much smaller. Also, the difference in seismic and tsunami arrival times would have been hours longer than for Sri Lanka. If my previous speculation about animals is correct, then, given comparable tsunamis, we'd expect a larger percentage of animals to die in Africa than in Sri Lanka, because in Africa the seismic warning from the quake would be harder or impossible to detect.

Don

  ----- Original Message -----
  From: Don Nield<mailto:d.nield@auckland.ac.nz>
  To: Don Winterstein<mailto:dfwinterstein@msn.com>
  Cc: asa<mailto:asa@calvin.edu> ; Randy Isaac<mailto:rmisaac@bellatlantic.net>
  Sent: Sunday, January 09, 2005 4:00 PM
  Subject: Re: tsunami impact on animals

  Don Winterstein wrote:

> Seismologist Chris Chapman was vacationing at a hotel about 30 km
> north of Galle, Sri Lanka, when the tsunami hit. Among his comments:
>
> "We heard two interesting stories about animals. An Englishman living
> with a Sri Lankan family near Matara fled to high ground when an alarm
> about the approaching wave was raised (they must have had a warning
> wave as we did). When he arrived, he was surprised to find the
> cattle, which roam freely, already there. Despite the utter
> devastation, no dead animals have been found in Yala National Park."
>
> Apparently the cattle were domesticated--but free.
>
> Chapman's "warning wave" was a precursor: "...The sea slowly rose a
> few metres to the level of the hotel's swimming pool and a small wave
> gently rolled through the ... hotel lobby." On seeing this he
> offhandedly remarked to his wife that there must have been an
> earthquake in the Indian Ocean. When he soon after noted the
> appreciable retreat of water from the beach, he had the hotel warn
> everyone to stay off the beach and head for high ground. No lives
> were lost at their location, and only minor injuries sustained.
>
> Although there's considerable anecdotal evidence, controlled studies
> to evaluate whether animals can sense impending earthquakes so far
> have proved negative. In this case the
> animals presumably felt the seismic waves from the earthquake,
> which would have arrived appreciably before the ocean wave. The
> animals apparently sought high ground in response. There's no known
> mechanism that would have allowed them to detect the tsunami itself in
> advance.
>
> Chapman's comments imply he didn't feel the quake himself.
>
> Don
>

>
  I find Don's comments a very plausibible explanation -- the animals
  deteced seismic waves at frequencies and amplitudes to which humans are
  insensitive. I would guess that the animals would not make an explicit
  connection with the need to go to higher ground. Rather, they would
  merely become disturbed and move away from exposed areas. That would
  mean that they would move away from the coast, and thereby automatically
  move towards higher ground or more dense vegetation that would provide
  protection from a tsumami.
  Incidentally, I read somewhere of a report from East Africa (I think)
  that some hippopotami were swept out to sea. It is understandable that
  because they were in a river they would not have picked up the seismic
  vibrations that are restricted to dry land.
  Don Nield
Received on Mon Jan 10 03:12:00 2005