纪录片《地球劫难日》 第17期 撞击坑（在线收听）

In a conventional view of an impact, we have a high speed asteroid which hits the earth's crust,

按照传统的大碰撞观点，一颗小行星高速撞上地壳

and makes a crater instantaneously which is very deep.

立即形成一个很深的撞击坑。

Immediately after the crater is formed, this deep shape the compressed rock underneath the crater rebounds

就在形成这个很深的撞击坑的同时，撞击坑下方压缩的岩层随即反弹，

and the crater expands to be a much shallower shape.

于是撞击坑扩张成比较浅的形状。

So under normal circumstance there would be a large shallow crater,

所以在正常情况下的陨石坑应该更大更浅，

but Johns believes that when a really massive meteor hits the earth something else happens too.

不过Jones认为这么大的天体撞上地球上肯定还会发生别的情况。

What we think happens is that in addition to the energy from the asteroid itself,

我们认为除了小行星本身释放能量外，

an enormous amount of energy is released when the crater here is transforming back to its shallow shape.

撞击坑变回到较浅的形状的过程中也会释放大量能量。

John's theory is that as the crust rebounds from the impact of the meteor,

Jones的理论认为，当地壳在陨星撞击后反弹时，

it generates far greater quantities of heat than anybody had thought possible.

会产生超出任何人想象的极高热量。

He built a computer model to see what would happen to a crater if this occurred.

他建立了计算机模型，研究撞击坑形成时可能发生的情况。

The impact causes a deep crater.

撞击造成了一个深坑。

This rebounds to create a wider, shallower one,

它反弹后成为一个更宽更浅的坑，

but then if the meteor is very large something new happens

可是后来由于陨石过于巨大发生了一些新的情况。

It melts the earth's crust and lava is released.

它熔化了地壳，熔岩被释放出来。