Scientists using numerous computer simulation models of giant asteroid impacts on the ocean have found that the farther out into the deepest areas of the ocean, the more distance the object is when it strikes the water's surface, has a profound impact on the potential for damage. In fact, given all the Hollywood-driven scenarios of massive tsunamis, virtual mountains of water crashing into coastal cities after an asteroid impact, it should be noted that such an event will likely never occur.
As Seeker reported this week, scientists at the Los Alamos National Laboratory in New Mexico have found that tsunamis rolling in and over coastal cities due to the impact of a massive asteroid are likely never to occur, because 70 percent of the Earth's surface is covered by water. The researchers studied different sized asteroids making impacts at different distances -- and different incoming trajectories and different water depths -- from the shoreline. They also studied the effects of asteroids that exploded as airbursts. As one might expect, asteroids that hit close to shore were devastating to coastal areas. However, as the distance from shore -- and the water's depth -- grew, the less likely the monstrous waves created by the impact would reach the shore as a danger.
"Movies like 'Deep Impact' and 'Armageddon' suggested that an ocean impact would produce a devastating tsunami that would affect everything along the shorelines surrounding an ocean basin... but I was skeptical," Galen Gisler, the scientist who led the project at the Los Alamos National Laboratory, told Seeker.
Researchers found that Gisler was correct with his original hypothesis. The three-dimensional modeling showed that the tsunamis portrayed in the movies were fiction.
"An asteroid impact is a point source and it only affects the immediate region around the impact point and moreover, to create a tsunami, you need something that disturbs the entire water column," Gisler explained.
A point source-generated wave loses its ability to propagate fairly quickly, the scientists found. As the Daily Mail noted, using the factors of a basalt asteroid, static air, and static water, "kinetic energy would be transferred to the water, and in the largest scenario, the visualization shows how a 250-meter-wide asteroid could create a transient crater, giving rise to a massive plume of water and water vapor."
As ScienceAlert reported, such a jet of water from the initial asteroid impact could reach from hundred of meters in height to a few kilometers. Still, even with so much water falling back into the ocean, the resulting colliding shockwaves in both the atmosphere and the water, plus wind resistance at the water's surface would work against the creation of a propagating wave.
Regardless, as Gizmodo pointed out, giant asteroids colliding with the ocean (or even exploding over it) are still incredibly dangerous, especially at point of impact -- just not in the area of creating a tsunami.
"The most significant effect of an impact into the ocean is the injection of water vapor into the stratosphere, with possible climate effects," Gisler said.
The release of water vapor into the upper atmosphere would only add to the greenhouse effect and contribute to the already runaway global warming problem facing the planet.
But the worst possible scenario, other than a direct asteroid impact on land? An airburst just off the coast. As Gisler noted, such a detonation near a "populated shore will be very dangerous" and could very well produce a tsunami like those seen in the movies.
The asteroid simulation study comes as a NASA scientist, Joseph Nuth, made remarks at a presentation in San Francisco on Monday that the Earth was unprepared to defend itself against a "dinosaur killer" asteroid strike. As the Inquisitr reported, Nuth warned that the Earth was somewhat due an extinction event-sized asteroid (considering the average time between such events is roughly 50-60 million years, and the last event occurred approximately 65 million years ago, contributing to the extinction of the dinosaurs) and "there's not a hell of a lot we can do about it at the moment."
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