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)
"I resented alimony."
The last legal form of indentured servitude.
Oh my goodness, would you look at that map...NO is doomed again! .
Not quite, there's also the H1-B Visa.
I knew if we were diligent we could work immigration into this thread...
Working in this country under H1-B Visa is voluntary, in more ways than one, as has become painfully obvious by now.
Try not "volunteering" to pay alimony, though, lol.
No one held a gun to my head to get married in the first place.
(If they had, I shoulda taken the bullet)...
I'll just choose to believe that any near Earth object of sufficient size to cause such devastation has been discovered, catalogued and monitored, so we'd have at least enough warning to get out of harms way. Of course, this one wiped out the majority of species in existence at the time, so getting away from and surviving the immediate effects of the impact would be no guarantee. Sunlight would be thoroughly obscured for quite some time, agriculture would fail and winter would be something else for decades or longer. Just surviving would be quite an adventure, to put it mildly.
My solution would be an effort to systematicly catalogue every object that crosses our orbit, with a program to consume every threat with robotic miners and factories. The impacts would never occur, and we get a bunch of cool stuff built in space.
The cataloging is already being done, of earth-orbit crossers, by Eugene Shoemacker's collegues. The challenge then is to make it economical with available technology, ie, make it worth someone's while(monetary incentive). Cleaning up space is a "nice" idea, so is cleaning up the litter on the street, but who does it for FREE? People have long thought of that, even hollywood in movies starring Bruce Willis, but be practical; going after asteroids to move them is not on the top of NASA's list right now, although they HAVE landed a probe on one already.
Twas thinking about it. I live at 3000' elevation, high in the mountains but at 20' above sea level you and hundreds of millions are GONE in a 300' high wave. What then would be a practical solution, something that you could do as a shelter to withstand 10 atmospheres of water pressure? A diving bell in the basement, an apollo capsule gumdrop, a thick-walled steel pipe, a ferro-concrete box or geodesic sphere...what? Since a 300' foot high wave will scour your city to bedrock, it has to withstand the bull-dozing effect from the debris, then pop to the surface with hull integrity still intact, then possibly survive for weeks in this vast floating sea of debris until it washes up on shore. Forget rescue, there won't be hardly anyone LEFT to rescue anyone else. TIDAL WAVE will be added to the Malthusian control mechanisms of war, disease, famine...since "moral prudence" didn't work very well. So, what is your design solution?
apoloptic = apocalyptic
The FEAR of the LORD is the beginning of wisdom. Figured out the Noah story long ago(15 cubits = 22' storm surge on the Indus River Delta)but the preparedness message is still the same. There are hurricane shelters spotted all along the US gulf coast, but there, with modern communications you don't get another Galveston 1900 where 6000 perished, people HAUL *** and get out of the way. Even with hours of warning the roads UPHILL will be jammed, so unless your car doubles as a surf board...So, "noah", you might want to troll around marine supply places, research facilities, to see what you could buy as some kind of cork/diving bell/pipe(something that can take 10 atm of pressure). As an architect I'd do a 8'I.D. geodesic dome/sphere 2 frequency icosahedron out of welded pipes/chicken wire mesh/ferro concrete w/extra conc in the floor(C.B. above C.G.). Sure people would laugh, they laughed at noah building a log raft out in his orchard....or you could be polite : your surplus diving bell stored in a storage shed. As a past dictator pointed out : the WINNERS get to write the history books...
December 2007 bump.
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