If it was known that there would be a M6 earthquake in Los Angeles, with a small chance that it would be a M7, and you were Mayor, would you evacuate the city? Or, just close and evacuate taller buildings and other structure that could be a problem in a 7?

Well, there is a similar situation today in New Orleans. The article quoted below, and linked, says New Orleans is not being evacuated:

"Landrieu has not ordered an evacuation of his city, most of which is below sea level and protected by a network of levees. But he said he would "strongly urge" about 900 people who live outside the levee system to leave -- and if anyone else is thinking about getting out, "now would be a good time to go.""

But, the National Hurricane Center gives Isaac a 6% chance of being a Cat 3 on Tuesday and a 8% chance of it being a Cat 3 on Weds.

The probabilities for Cat 4 for the same days are 1% and 2%
http://www.nhc.noaa.gov/text/refresh/MIAPWSAT4+shtml/272045.shtml?

Isaac is big but not as big as Katrina, which was huge. Katrina was a cat 5 hurricane that weakened as it came ashore to Cat 3. I'm curious whether the huge storm surge was in part the effect of it having been a cat 5.

Isaac is not even a hurricane yet but very likely will be one at the next advisory.

There have been hurricanes that rapidly intensified in the Gulf: Opal (hit Florida panhandle) and Charlie (hit Gulf side of Florida peninsula) come to mind.

But the NHC does not expect rapid intensification for Isaac.

I'd be not sleeping too well if I was mayor of New Orleans. He may have done the right thing, but it is a risk...

If we wake up tomorrow morning and Isaac is a rapidly intensifying Cat2 or 3, it is likely too late to evacuate everyone out of the city.

Chris

• Isaac and New Orleans