Underground cables have more expensive set up costs, lower lifetime, and higher maintenance costs. The price you pay for electricity doesn't even come close to justifying burying power lines. There's also the ecological stuff if you find that a reasonable argument. Bottom line, burying power cables just so you don't have to light a candle for a night isn't worth it.

Until earthquakes.

Depending on where you are in the world, earthquakes are much rarer then insane storms. I'm speaking as a Floridian. I'm fairly ignorant on this issue, but would it be that difficult to use one or the other depending on which natural occurrence is more likely? Or is this also a cost issue?

Massive cost issue, plus some technical issues.

According to this document [1]:

"The North Carolina Utilities Commission studied the cost of placing Duke Power’s distribution facilities underground and found it would cost more than $41 billion, resulting in a 125 percent increase in customer rates."

[1] http://www.sceg.com/NR/rdonlyres/465E6534-2FFB-4069-BF84-814...,

Underground cables have many problems like rats (and other vermin) or people harvesting copper/metals.

Do they? Here in Germany the entire cabling within cities is underground, only the high voltage long distance lines are above ground. I've never heard a story about people stealing underground cables (they do steal e.g. train track above ground cabling). That also wouldn't make sense, digging up those cables is much more effort than taking them down from a post.

I've also never heard stories about issues with rats.

Power outages still happen, but they are quite rare - in 30 years I can only remember twoish.

Rats are a common menace with all sorts of cabling. Large parts of scotland recently lots broadband due to rats eating cables (http://www.theregister.co.uk/2011/10/12/dirty_rat_downs_virg...).

Apparently it's the insulation on the wires that they like.

Really? Rats and copper harvesters?

Like it's gonna be some unprotected plastic cables 1 foot under the ground?

I don't know but I've heard stories. Stealing cables underground is not common but it happened. And rats and underground water is quite a problem for underground (copper) cables.

Sometimes they don't even steal the cables... This guy just liked the sparks. http://www.westvalleyview.com/main.asp?Search=1&ArticleI...