November 19, 2006
Chevrons Provide Evidence For More Frequent Asteroid Impacts

The New York Times reports on an international collaboration of scientists called the Holocene Impact Working Group which believes asteroids hit the Earth far more often than previously thought and 600 feet high chevrons 3 miles from the ocean in Madagascar are evidence for a massive asteroid 4800 years ago which a caused tsunami wave. (and the article is a good primer on how geologists look at soil samples for evidence of past events)

Scientists in the working group say the evidence for such impacts during the last 10,000 years, known as the Holocene epoch, is strong enough to overturn current estimates of how often the Earth suffers a violent impact on the order of a 10-megaton explosion. Instead of once in 500,000 to one million years, as astronomers now calculate, catastrophic impacts could happen every 1,000 years.

The researchers, who formed the working group after finding one another through an international conference, are based in the United States, Australia, Russia, France and Ireland. They are established experts in geology, geophysics, geomorphology, tsunamis, tree rings, soil science and archaeology, including the structural analysis of myth. Their efforts are just getting under way, but they will present some of their work at the American Geophysical Union meeting in December in San Francisco.

This year the group started using Google Earth, a free source of satellite images, to search around the globe for chevrons, which they interpret as evidence of past giant tsunamis. Scores of such sites have turned up in Australia, Africa, Europe and the United States, including the Hudson River Valley and Long Island.

First of all, isn't it great that Google Earth is speeding research into the asteroid threat? Is it possible for us non-experts to look at Google Earth pages and recognize Chevrons? Can someone collect a set of Google Earth URLs that display chevrons from around the world?

The chevrons these scientists are finding are all pointed at nearby large bodies of water. So all over the world there are signs of past massive waves which have slammed inland at various times in history. But scientists who study near earth asteroids are skeptical because they find too few asteroids to account for the number of chevrons claimed to be from mega-tsunamis due to ocean asteroid hits.

Asteroid detection and deflection research already struck me as woefully underfunded before I read this article. Now the possibility that major asteroids might strike the Earth far more frequently than previously believed makes the urgency of asteroid research even greater.

If someone spots an asteroid tomorrow that is going go hit the Earth 2 days later we'll all spend the following 2 days feeling really really stupid for not doing more to prevent an entirely avoidable threat to our existence. Why not avoid that outcome and find the orbit of every asteroid out there?

Share |      Randall Parker, 2006 November 19 09:16 AM  Dangers Natural General

Bob Badour said at November 19, 2006 10:19 AM:

If one clicks the Multimedia link (the picture of the map) on the NYTimes article, one can see what the chevrons look like--in case anyone wants to hunt for more of them.

Steel Turman said at November 20, 2006 7:21 AM:

And there I was, just having a nice day.

It's always something.

An impact would be just the thing to shake us out of our petty self-centered mindset.

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