"If this thing hit the Pacific Ocean anywhere, the whole of the Pacific rim would go, tidal waves, whatever.Tidal waves???????? Ummm, don't think so, Doc. The article says he is an astronomer (hey, I have a telescope too), but what is he a doctor of, podiatry?
By the way, just what we need, not one big asteroid coming our way, but millions of bits of busted-up, radioactive meteor surrounded by a cloud of radioactivity, headed straight for our vicinity.
Back to the drawing board, "Dr." Ford.
Let's see. . . rock is roughly 4KM in diameter. Assume a mostly iron composition: Iron is 7874 kg/m^3. Assume roughly spherical shape: that gives you roughly 270 billion cubic meters of iron. The math gives you a bit over 2 billion metric tons of iron with a total relative velocity difference of roughly 50 meters a second. That's 5.25 quintillion joules of energy. That's a BIG bang. . . .