This is an interesting idea tackled in
Greg Bear's book
The Forge of God.
I(also)ANAP, but Bear's description is quite illuminating.
Aliens who don't like us throw a micro-
black hole at the Earth. The people who see it arrive get a pretty awful
dose of radiation. The black hole manages to pass through
the Earth almost frictionlessly, so it settles into a nice regular orbit
inside earth.
This becomes noticable to us
earthlings as an increase in earth
tremors. Current
seismological technology allows us to estimate not only the position, but the
depth of
earthquakes. So with a bit of work, international teams of
geologists manage to track the motion of the black hole by correlating vibrations (a kind of solid-medium
sonar). That's when we figure out what they hit us with.
The first large-scale effects are an increase in intensity of earthquakes and
tsunami. In
Bear's book, it is eventually the
vibrations of the
oscillating black hole that
destroy the earth*, not simply loss of matter. IIRC, this takes two weeks, not a matter of seconds.
On a side note: I found reading this
book unusually
exciting because
it fell apart. For the most part I was reading a big bundle of pages that had fallen from somewhere in the middle of the book. This meant that I had no idea
how long the book was until I finished the loose bit - I really had no idea what the ending might be, because I couldn't guess how many pages the author had to
wrap the story up.
* or maybe they don't, I'm not going to
spoil it for you : )