Putting the Richter Scale in perspective.

[amerikat]

Look at the energy release difference between a 6.0 and a 7.0.

Richter TNT for Seismic Example
Magnitude Energy Yield (approximate)

-1.5 6 ounces Breaking a rock on a lab table
1.0 30 pounds Large Blast at a Construction Site
1.5 320 pounds
2.0 1 ton Large Quarry or Mine Blast
2.5 4.6 tons
3.0 29 tons
3.5 73 tons
4.0 1,000 tons Small Nuclear Weapon
4.5 5,100 tons Average Tornado (total energy)
5.0 32,000 tons
5.5 80,000 tons Little Skull Mtn., NV Quake, 1992
6.0 1 million tons Double Spring Flat, NV Quake, 1994
6.5 5 million tons Northridge, CA Quake, 1994
7.0 32 million tons Hyogo-Ken Nanbu, Japan Quake, 1995; largest Thermonuclear Weapon
7.5 160 million tons Landers, CA Quake, 1992
8.0 1 billion tons San Francisco, CA Quake, 1906
8.5 5 billion tons Anchorage, AK Quake, 1964
9.0 32 billion tons Chilean Quake, 1960
10.0 1 trillion tons (San-Andreas type fault circling Earth)
12.0 160 trillion tons (Fault Earth in half through center,
OR Earth's daily receipt of solar energy)

[Kurt_and_Hunter]

1. Yes, the Richter Scale is exponential

It is really something to recognize that the Anchorage quake in the 1960s was 100 times more powerful than the recent Haiti quake.

That said, Richter must be combined with depth... the Haiti quake was very shallow and thus disproportionately destructive to structures. (When I first heard there was a 7.0 in Port-au-Prince I wasn't expecting quite this level of destruction.)

And local geology makes a difference... firmness of soil and such.

I applaud the general thrust of your post, that the recent news report of a 6.0 quake is a smallish quake despite being "only" one less than Haiti.

[FarCenter]

2. You can't get much beyond 9.0

The earth's crust is only so thick, rock is only so strong, and faults break on segments of finite length.

Therefore, there is a limit to the amount of stored energy that can be released in a single earthquake.

[TheWraith]

3. Kicked and recommended.

An important reminder for the science-challenged around DU.

[JVS]

4. 1999, everything between LA and NYC slips under the crust and East Coast and West Coast...

rappers unite.

[Kurt_and_Hunter]

5. k