Posted on 05/12/2006 11:49:03 AM PDT by blam
Tsunami risk of asteroid strikes revealed
18:18 12 May 2006
NewScientist.com news service
Jeff Hecht
The researchers modelled the asteroid impact believed to have led to the demise of the dinosaurs – this frame shows tsunami wave heights 4 hours after the impact of the 10-kilomtre-wide asteroid (Image: Steve Ward)Related Articles
Tsunamis triggered by asteroid impacts cause a disaster similar to the 2004 Asian tsunami once every 6000 years on average, according to the first detailed analysis of their effects.
Researchers have assumed that tsunamis would make ocean impacts more deadly than those on land. But Steve Chesley at the Jet Propulsion Laboratory in Pasadena, and Steve Ward at the University of California at Santa Cruz, both in the US, are the first to quantify the risks.
The pair first calculated the chance of various size asteroids reaching the Earth's surface, and then modelled the tsunamis that would result for asteroids that hit the oceans.
For example, the model shows that waves radiating from the impact of a 300-metre-wide asteroid would carry 300 times more energy than the 2004 Asian tsunami. You can view movies of impact simulations in the North Atlantic, South Atlantic, Gulf of Mexico and Pacific (all in .mov format).
Fifty million people
To accurately assess the overall impact-tsunami risks, the analysis included the full range of asteroid sizes, including the smallest asteroids capable of penetrating the Earth's atmosphere. These are between 60 and 100 metres, depending on their composition.
The most common asteroids, between 100 m and 400 m, would yield tsunami waves up to 10 m when they arrived at the coast. A total of about 50 million coastal residents are vulnerable to such waves, though no single impact would affect them all. The researchers predict a tsunami-generating impact should occur about once every 6000 years, and would on average affect over one million people and cause $110 billion in property damage.
The study also showed that asteroid impacts in the 300-metre class might be similar to the huge tsunamis thrown up when massive chunks of rock break from the sides of volcanoes and fall into the ocean. These events are also thought to occur roughly once every 6000 years.
The analysis confirms suspicions that tsunamis are the biggest risk posed by asteroid impacts. The risks from climate effects of big impacts – through dust and smoke that blocks out the Sun – are about two-thirds that of tsunamis, while those of land impacts are about one-third of the tsunami risk.
Hurricane aspects
"There still are a lot of uncertainties," Chesley cautions. The solar system's population of 100 m to 400 m asteroids is poorly known, as are coastal population distributions. A big question is how the waves would behave when they reach the shore; successive wave peaks are much closer together in asteroid tsunamis than in earthquake tsunamis (see a simulation of an asteroid hitting the water, here).
But the ultimate uncertainty is when and where an asteroid might hit. "Asteroids sprinkle down pretty much at random," says Ward, "They don't pick out California or Florida."
And, like hurricanes, location is the key. Hurricane Katrina became America's worst natural disaster in living memory not because it was the biggest storm, but because it made a direct hit on vulnerable New Orleans.
But while hurricanes are difficult to predict, they do follow the same general paths. Asteroids come out of the blue – literally.
Journal reference: Natural Hazards (vol 38 p 355)
hehe --
Our ***mountain*** home & property in Otto, NC becomes ocean-front property. 2910' ASL here baby!!!
We're safe, "too bad for you!"
Spoken with the Liberal mindset
Especially bad news for Cuba!
Since the bird flu bs isn't taking hold, I guess the mass media is gonna try and wip up asteroid hysteria (again).
Looks like New Orleans gets smacked by God ! Will FEMA come to the rescue . Can you surf in a school bus ??
I went to the article, looking for a legend and perhaps a time-lapse as far as this coastal inundation graphic, hoping to see some explanation as to the color coding. I assume it's wave height along the coastline, but then you've got the whitish areas going halfway up the Mississippi Valley, hundreds of miles inland. There has to be an elevation component to it, looking at the "islands" in TX, TN, MS, AL, GA and SC.
Play the QuickTime animations. Press the "pause" button when the legend pops up. Then memorize the color codings when you watch the animation. I think the highest waves (orage) were 65 meters high (200 ft).
This story is made for George Carlin's Hippy Dippy Weatherman.
I did that, and unless I'm misinterpreting, none of those showed the effects on land. They stopped at the shoreline.
Also Footfall, except the aliens are using the rock to wpe us out.
You mean like the one that got the "vapors" when Larry Summers said that there might be a difference between boys and girls?
"That" type of MIT scientist?
Yup,that's the kind.But be aware of the fact that these fine folks would be able to confirm the level of damage from having a chunk or stone 1/4 mile across fall on your head.
Not to discount the salts, but at some point, the vaporization would tend to leave behind the salts.
So, given the prevailing winds, the damage might be greatest immediately downwind of an impact. That's to say a Pacific
strike off of CA would do a number on their agricultural lands.
And while salt isn't effective below a certain temperature for melting ice, there would be the potential for increased
flooding from mountain snow packs too.
To paraphrase another Freeper's post a few months back, People who study oceans don't live near them.
I would speculate that if my N/E/W/S "forty" was closer than that to the impact, I probably would want to know the level of damage...
Interesting. As far as this specific Gulf graphic, I find myself wondering about all that water, at least halfway up the Mississippi Valley, and the stress it would exert upon the New Madrid fault, too. As bad as the death and destruction from coastal inundation would be, it's slowly dawning upon me that it would just be the beginning.
New Orleans goes under again!
Yup. Have you considered the 'cosmic winter' that is sure to follow from all the sulfuric acid droplets blocking the sun for years.
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