Monday Science

This week's science:

• Ed at Not Exactly Rocket Science looks at the seven habits of sucessful toads: Toads are an evolutionary success story. In a relatively short span of time, they diversified into around 500 species and spread to every continent except Antarctica. Now, Ines van Bocxlaer from Vrije University has uncovered the secrets of their success. By comparing the most home-bound toads with the most invasive ones, she has outlined seven qualities that enabled these amphibians to conquer the world. In a common ancestor, these seven traits came together to create an eighth - a pioneer's skill are colonising new habitats.


• Brian at Laelaps looks at the fearsome short-faced bear: The quiet of my evening wildlife watching was suddenly broken by a thick Boston accent. "Oh my gawd! Look! It's a grizz! That's the last animal I needed to see! It's a grizz!" He was right. Lumbering across the valley was a big dark shape that could only be a bear. It was not very close, being little more than a dot moving along the distant treeline, but through the zoom lens of my camera it was just possible to make out the hump that distinguishes black bears from grizzly bears. It was the closest I would get to Yellowstone's largest predator during my visit to the national park (at least that I know of), but in the not-too-distant past an even larger cousin of the grizzly roamed much of North America.


• Chris at Highly Allocthnous wonders about Haiti's seismic future: It's now been just over 3 weeks since a magnitude 7.0 earthquake hit Haiti, devastating the capital Port-au-Prince and many other surrounding towns and villages. The sheer scale of the disaster - the tens, even hundreds of thousands who have lost their lives, or their homes and families - has been quite overwhelming. As the country struggles to recover and rebuild, and with aftershocks still occasionally shaking things up, one question that people want answered is, are we safe yet? When is the continued seismic activity going to stop? Will there be another devastating earthquake in the future - and if so, when? And what about the rest of the northern Caribbean?


• Phil at Bad Astronomy talks about clusters and stars: Purty, ain’t it? That’s NGC 3603, a very large star-forming region in our own Milky Way Galaxy, lying about 20,000 light years away. It can only be seen from the southern hemisphere, which is why the European Southern Observatory folks got this image using the ginormous Very Large Telescope, an 8-meter behemoth in Chile (and actually, Ginormous Telescope would be a cool name). Not too long ago — no more than a million years, give or take — a lot of the stars forming the central cluster there were born. There are so many that they appear to overlap, but that’s an illusion due to the blurring of the image from the Earth’s atmosphere (and the nature of light itself only allows us to make star images so small). Lost in that crowd is a star designated NGC 3603 A1, and it is the most massive star to ever have its mass directly measured. It’s actually a binary star, two monsters locked in a gravitational dance, orbiting each other once every 3.77 days — which right away tells you this is a special pair, possessing enough gravity to toss themselves around that rapidly.


• And Erik at Eruptions looks at the Yellowstone caldera and swarm eruptions: With all the talk of the current Yellowstone earthquake swarm, I thought it would worth it to write a post on the the structure and caldera - and why we get earthquake swarms that are structurally rather than magmatically-related. First off, lets think about why calderas formed. This is relatively simple - at least superficially. The land (or volcano) above a magmatic system is partially supported by that magma, especially because magma is hot and buoyant. The isostatic support by the magma holds up the land surface or volcanic edifice, so when an eruption expels a large volume of magma, this support is removed. This collapse forms the caldera - the negative topographic expression of the eruption. The collapse of the land surface plays a dual role - not is it a result of the eruption, but also helps the eruption along, like a piston pushing of hot gas out of a cylinder. After the eruption, the collapsed caldera continues to subside as the isostatic equilibrium is reached. After the caldera-forming eruption {caution, large PDF}, the system may have eruptions that produce resurgent domes in the middle of the caldera as the last dregs of the caldera-forming magmatic system leak out. This is referred to as the "caldera cycle", originally defined by Howell Williams for the collapse of Mt. Mazama ~7,700 years b.p. (see below).

Enjoy!