当地震发生，它会从震源产生一个速度为数公里每秒的扩散的波。
When an earthquake occurs, it generates an expanding wavefront from the earthquake hypocenter at a speed of several kilometers per second.
这个成分，是vcosθ,我们叫做径向速度-,等于-100，公里每秒。
So it is this component, v cosine theta - which we call the radial velocity-- that is minus 100 kilometers per second.
这种以每秒数百公里的速度旋转的运动，可能会使圆盘上的物质呈现出螺旋形状。
This spinning motion, at speeds of hundreds of kilometers per second, may cause matter in the disk to take on a spiral shape.
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