Well, yes, I believe the US is viewed with some suspicion. But more I think it’s a bit of human nature to take certain warnings with a bit of skepticism. Now, if the USA said, we have information that a big wave is going to wash over all of your tourist areas (and this before anyone alive had much of an experience with it), and the person being told this is not a scientist and maybe even not particularly clever (being a political appointee or recipient of some patronage), they might need to verify with the proper people what they should do. As an American you might find this tough to believe, but in some countries, and Thailand is one of them, things tend to work in a strict hierarchy. Yes, sometimes the hierarchy is not followed, but when the hierarchy breaks down the result is more often than not pure chaos. Someone will be worried about who will be to blame if a needless panic is caused in a tourist area that generates a lot of revenue. So a proper chain of command will be followed.
Heck, let’s look at it from a personal point of view. Let’s say a friend called with urgent news that a meteor was about to strike Lansing. We’ll even say it’s your most trustworthy friend, someone who would never yank your chain. Would you drop the phone and barrell out of town at full speed. Or would you stop, think about what you need to do, maybe flick on CNN really quick to verify what’s really happening, call your family and friends and alert them, grab your dog, etc? All of those things are human nature you’d have to fight against. When the chain of information is longer, and the information less certain than “Fire!”, it’s probable that there will be delays. Don’t you remember some personal disbelief and slowness to react on 9/11? This is how we process information that is incredulous and threatening.
Whether the USA is in the habit of contacting other countries with “bullshit warnings” is really beside the point. Maybe they’re not in the habit of receiving any emergency warnings from the USA. Is there a process in place to get the information to the right people quickly? Thailand (nor Indonesia, nor Malaysia, nor Sri Lanka, nor Somalia) are vital enough to US interests that we have a direct line from our halls of power to theirs. Sure, we have the phone number. And if GWB or Colin Powell or somebody called them and told them to evacuate Phuket the Thais would have probably taken it very seriously. But it still would have been some time, and most likely too late, before it wound back down through the proper channels.
Just because it was a massive undersea earthquake, was it inevitable that there be tsunamis following it?
There was (until this one) the world’s most powerful earthquake for four years just 3 days before (23rd December) at the other end of one of the tectonic plates involved down near the Macquarie Islands south of New Zealand.
But, according to this BBC report, because it was a horizontal shift, there were no tsunamis similar to the catastrophic one generated in the Indian Ocean.
Another report I read said that the noise from an approaching tsunami would be very, very loud. On the scale of a jet taking off or something. But even when you hear that, you’ve got maybe five minutes to get to higher ground.
Just to add one more source of radios: you’ve got to count alarm clocks in there.
The key is whether there is significant vertical displacement (or a vertical component of displacement) of the sea floor during the quake, because a movement of the seafloor up or down will disturb the overlying water. That will be determined by the kind of fault along which the quake occurs.
With an event like the Macquarie Island quake, the fault that ruptured appears to have been a strike-slip fault. This kind of fault is characterized by mostly horizontal displacement; the two sides of the fault are basically grinding side-by-side in opposite directions, and there is no significant vertical motion on either side. So, there isn’t any displacing force to generate a tsunami.
In contrast, Sunday’s quake was on a subduction zone type of plate boundary, which is essentially a very large thrust fault. In thrust faults, one side of the fault is being pushed up over the other, so most of the displacement has a vertical component. A large enough earthquake will push up a portion of the sea floor, basically giving a huge shove to the overlying ocean water. You would then definitely expect a tsunami.
Ok, thanks; so a seismograph reading won’t tell them on it’s own if there ought to be tsunamis, but then pinpointing the location and looking at maps of the undersea geology will?
The fastest way to know whether a tsunami has been generated, and the only way to have a warning generated in time to help people, is to have data from tidal gauges spread across a large area, so that differences from the norm can be tracked and the wave modeled. That also requires, by the way, a standing program of collecting tidal data under normal conditions so that anomalies can be spotted. If, by some magical means, we could have tidal gauges scattered across the Indian Ocean tomorrow, and another tsunami occurred the day after, scientists would still be hard-pressed to generate an appropriate warning - because no baseline currently exists for comparison.
Remapping the sea floor bathymetry to confirm displacement requires driving a ship equipped with side-scan sonar or the like over the fault, although some estimate can be made after gathering enough seismic data about the strength of the quake and the motion along the fault. This information wouldn’t be available until after the tsunami had hit. Note that in the articles discussing the amount of sideways movement of the Nicobar Islands, we still won’t know for sure how much displacement there has been until someone gets out there with the instrumentation to measure it.
So any earthquake (at sea) on a similar boundary would also generate a tsunami? Or could this earthquake have acted similarly to the Macquarie one and slid horizontally instead of vertically?
Yes, but could experts have looked at a quake’s location wrt known tectonic boundaries, etc. and been able to say with any confidence that (like at Macquarie) there would be horizontal slippage, or vertical slippage?
The surest way to detect a tsunami is to have a number of bouys in the sea that measure the height of the ocean waterline, right? It’s a bit tricky because you’ve got waves, and a tsunami wave in deep sea is only a few centimeters high. The key is length, and if the bouy detects a prolonged average elevation of 3cm, that’s when the readings will say ‘uh-oh’. I think this is the main system that protects Hawaii, after the tsunami hit that island hard.
Well I guess the conference on the new sattelites and warning system mentioned above in Februari will at least make sure that will be taken seriously and receive proper funds. This is one big disaster though, it won’t be forgotten easily.
Sometimes disaster movies are good for you; when one of these big Hollywood production Tsunami disaster movies was running, the BBC broadcasted a programme about an island I think near Africa that consists of a big mountain which has a faultline almost straight through the middle. If the upper half would slide into the ocean, it would create a tsunami that would hit nearly the whole U.S. shoreline with an enormous wave that would seriously hit everything about a 100 miles inland. Scary thoughts. The Netherlands wouldn’t deal all that well with one either, as lots of our highly populated areas are in fact below sea-level.
With many faults, there is more than one component of slip, so that the two sides of the fault are moving past each other at some angle other than 90 degrees (e.g. pure thrust motion) or 0 degrees (pure strike-slip). However, a thrust fault is called that because, by definition, most of the slip does have a vertical component. That kind of motion would be expected along subduction zones in general. Pure strike-slip motion on a thrust fault would not be expected.
So, the Sumatra fault would not move in the same way as the Macquarie fault, nor could it have given other details of the geologic setting, e.g., known manner of movement of the Indian plate beneath the Burma plate (at an angle of roughly 45 degrees to the orientation of the Sunda Trench close to the epicenter). Pure strike-slip motion would have required the Indian plate to suddenly head in a different direction, to the NW (ain’t gonna happen!).
Now, upon receiving enough seismic data to suggest that the quake occurred along the subduction zone, scientists would have expected mostly vertical slippage on the Sumatra fault. That was why the geologists at the Pacific Tsunami Warning Center did send out an early warning about the possibility of a tsunami. However, that bit of knowledge doesn’t provide any way to be any more precise re tsunami size estimate, extent of coastal impact or times of arrival.
There are apparently reports in Bangkock’s The Nation newspaper that officials were hesitant to issue an alert because it would hurt tourism if no tsunami struck. MSNBC / Keith Olbermann Report .
While it may provide some sense of schadenfreude to consider bureaucrats sitting around arguing in comfort while their fellow citizens are destroyed, it should be noted that Thailand was struck within 35 minutes of the quake and most of India was hit in less than two hours. The scientists could have leaped to their feet and unanimously declared their intent to take all appropriate measures to issue a warning and it would have had no serious effect on the disaster. The infrastructure is not in place to either warn or to move sufficient people to have had any significant impact in reducing the loss of life.
were y’all passing notes during emergency preparedness class?
i remember seeing a report on earthquake preparedness that showed a school class chanting a nifty ditty about earthquakes, volcanos, and tsunamis. the report mentioned that schools in ca, or, wa, b.c., ak, and hi all have classes on what to do during whatever disaster may happen in their area.
from what y’all are saying they must have decided what emergencies are more likely to happen and concentrate on them. i would think that san fran. wouldn’t need volcano prep, but i am rather surprized they wouldn’t have tsunami prep.
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Here is an animation of the tsunami covering the Bay of Bengal. Note that all but the most distant shore of the most Eastern section on India had already been engulphed within 120 minutes of the shock. Now think how long it took to clear out Manhattan on September 11, 2001 with every television in the city broadcasting the event live…
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tomndebb, do you have a key for the meaning of the blue and red on that .gif? It could be water levels relative to sea level, because you see what looks like energy reflecting from land and from shallows.
It helps that doing a Refresh re-runs the .gif three times.
