For all you Christchurch guys and girls I hope this helps you to understand what is going on in your part of New Zealand
A little different way of explaining and actually seeing the mechanics of earthquakes that I know you can appreciate.
A little Engineer's refresher course.
Earthquake explained so you can remember
What's the difference between an oscillatory and a trepidatory earthquake?
1. This calculation is just for engineers:

2. And this one is for ignorants --like you and me [MOD: may not be safe for work or young eyes]:
This is a trepidatory earthquake:
http://i366.photobucket.com/albums/oo106/dbcunnz/Pic1.gif
This is an oscillatory earthquake:
http://i366.photobucket.com/albums/oo106/dbcunnz/Pic2.gif
And this is a combination of both: (trepidatory and oscillatory)
http://img267.imageshack.us/img267/7816/pic3.gif
Science is beautiful when it is well explained...
. . . and now you know.
Doug
[MOD: I've removed the embedded pics, but left the links. Note: I'm not being a prude, but these pics are not entirely appropriate, I think this is a suitable compromise]
A little different way of explaining and actually seeing the mechanics of earthquakes that I know you can appreciate.
A little Engineer's refresher course.
Earthquake explained so you can remember
What's the difference between an oscillatory and a trepidatory earthquake?
1. This calculation is just for engineers:

2. And this one is for ignorants --like you and me [MOD: may not be safe for work or young eyes]:
This is a trepidatory earthquake:
http://i366.photobucket.com/albums/oo106/dbcunnz/Pic1.gif
This is an oscillatory earthquake:
http://i366.photobucket.com/albums/oo106/dbcunnz/Pic2.gif
And this is a combination of both: (trepidatory and oscillatory)
http://img267.imageshack.us/img267/7816/pic3.gif
Science is beautiful when it is well explained...
. . . and now you know.
Doug
[MOD: I've removed the embedded pics, but left the links. Note: I'm not being a prude, but these pics are not entirely appropriate, I think this is a suitable compromise]