Christian Koeberl is a professor of Impact Research and Planetary Geology at the University of Vienna and an Asteroid Day Expert. In this post, he answers a user-submitted question. Do you have an asteroid related question? Submit it here.
Many countries have asteroid/comet impact craters, but it seems there is no crater known in Spain. Is Spain a safe place? 😉 Or did people not yet look for craters? Or is the erosion faster than in other countries?
Christian Koeberl answers:
“There are many countries on Earth – and huge parts of the surface of our planet – that do not “have” an impact structure. On a map of the distribution of impact craters on Earth one clearly sees that the CONFIRMED impact structures are not homogeneously distributed on our planet. This is the result of a complex interplay of geological and also human factors that affect the preservation and discovery of impact craters on Earth, even though they form randomly across the Earth. The are are several issues that need to be considered:
- a) the age of the continental crust (the older the more likely that it contains evidence of an impact event);
- b) geological processes can lead either to covering up impact craters with younger sediments, or obliteration due to erosion, subduction, mountain.building, volcanism and many other processes;
- c) it is easier to discover impact craters in less vegetated areas, and
- d) several countries have had intense search programs while others did not.
And even if crater-like structures are found, they need to be rigorously investigated to see if there really is unambiguous evidence for impact. So all this together leads to the observed uneven distribution. Neither Spain (nor any of the other countries without impact craters) are more safe, its just that either none is preserved or none is discovered so far.”
So there you have it. Spain isn’t a magical place that asteroids just stay away from. Nevertheless, I can still recommend it as a holiday destination – it’s magical in many other ways and certainly worth a visit. Just don’t go looking for impact craters.