Posted on 12/29/2004 8:06:01 PM PST by woofie
The ground below Albuquerque was still reverberating Tuesday from the massive Sumatra earthquake two days earlier.
In the office of New Mexico Tech seismologist Susan Bilek, meanwhile, the reverberations are likely to last a lot longer, as Bilek tries to make sense of what happened.
Sunday's earthquake continued to register Tuesday on the instruments at the U.S. Geological Survey's Albuquerque Seismological Laboratory.
The quake demonstrated that when hit hard enough, Earth "rings like a bell," according to John Derr, a seismologist with the Geological Survey in Albuquerque.
The frequency at which Earth rings is far lower than any ordinary bell, beyond anything you could hear. But when struck with the force of Sunday's magnitude 9.0 quake, the ringing can last for days.
Located at Kirtland Air Force Base, the Survey's seismometer continued to show weak echoes of the quake Tuesday afternoon in the form of pulses of movement in the Earth's crust every five to six minutes.
The movement is too small and gentle for a person to feel, but is easily detected by the sensitive instruments used to monitor earthquakes around the globe.
The Survey's Albuquerque Seismological Laboratory is a worldwide center for collecting the sort of data scientists like Bilek need in order to understand the Sunday earthquake and its implications for the future.
An assistant professor at Tech in Socorro, Bilek studies the way earthquakes of varying size can create massive and destructive tidal waves.
Bilek studies "subduction zones," areas like the edge of Sumatra where one of Earth's continental plates is slowly sliding beneath another.
"Sliding" makes the movement sound smooth and easy, but it really happens in little jerks because of the friction between the two plates. Strain builds up, then breaks loose, moving in some cases large distances, releasing pent-up energy in the form of an earthquake.
It also raises the ocean floor, triggering a tidal wave.
"One of the plates sort of pops up," Bilek said. "That's displacing a huge amount of water when that happens."
That is exactly what happened in September 1992 off the coast of Nicaragua. The Cocos Plate, slipping beneath the Caribbean Plate, triggered an earthquake and tsunami that killed hundreds.
Bilek said the quake was unusual because the size of the wave seemed large relative to the size of the quake.
"You might not have expected it to produce a large tsunami," she said. She and her colleagues have been studying the seismic conditions that distinguish subduction earthquakes that produce big tidal waves from those that don't.
But in the case of the world's massive subduction quakes, there is little question that a tidal wave will form.
That is what happened in Alaska in 1964, when a magnitude 9.2 earthquake triggered tsunamis that killed more than 100.
I read today that the expected animal deaths in the coastal areas hit by the tsunami have not been discovered. This could be due to the fact that rescue/reporting has been focused on human casualties. But I the article mentioned that many animals might have "sensed" the threat in time and moved inland, thus saving themselves. I wonder if this will be proven.
A dogs hearing is much more acute than ours ...I think animals "feel the vibes" and flee
Animals are amazing. Perhaps, although we may "understand" nature more, they may be more "in touch".
Or just washed out to sea.
And perhaps, swam back?
PS: If so, then why not the human casualties, who were found after the wave slowly receeded? Once drowned, they were found were they were laid by the waters, already dead. IMO, you misunderstand the entire dynamic.
Sorry, nothing personal.
They either went to higher ground, or were swept out to sea and swam back, or were swept out to sea and neither swam nor floated back, or larger ones were not easily moved from their places, or smaller ones are already buried in sand and debris, or the reports are wrong, or some combination. I think that exhausts the cases, and if so, the preceding statement must be true, tautologically.
It's inaccurate to claim I misunderstand the dynamic. I just suggested an additional case. I DON'T understand what dynamic would result in other creatures being disposed differently. That's a different thing.
I speculate that anything we have heard so far is speculative, not that there is the least thing wrong with that. ;-)
Well, hmmmmmmmmmmmm... curious.
More likely, I speculate, animals may have felt the seismic ground wave, or noises made locally by its passing. Cats, for instance, have a superb sense of balance, so I think they should be able to detect very subtle movements.
Humans have become terrible listeners since they stopped being hunters and gatherers. Just ask your friends ;-)
The fact is, nobody knows at this time what became of the animals, and local authorities are only just learning about what became of the human inhabitants -- although this is becoming horribly clearer by the hour. It's just hard to fathom a catastrophe of this magnitude in this day and age.
My point was about animals being able to "sense" disaster before humans could. IMO, this could in fact be true, for whatever reasons.
In this case, if all of the animals were drowned or washed out to sea, this should in time become evident and would reinforce the argument (in either direction).
Well, this was precisely my point!
Is it too soon still to make a Michael Moore joke?
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