An underground power grid in the best cases should be less susceptible to the effect of electrical storms. The American Transmission Company cites numerous reasons why it do not bury their transmission lines underground (e.g. environmental concerns, cost of installation and repair, etc.).
The linked article goes into extensive detail about the disadvantages and initial costs of putting in underground lines. The article does not factor in the maintenance costs of above and below ground installations.
With storms getting worse (Maryland, DC and Northern Virginia have weathered heavy storms this week), might underground lines prove more resistant to storm-related power outages?
http://www.atcllc.com/IT5.shtml

Buried services are a double edged sword. They are less vulnerable to tree damage but they can be flooded more easily and when they do fail they are a lot harder and more time consuming to fix.
Since one of the big considerations in a hurricane is the flood (surge tides) the flooding can't be ignored.
Of course retrofitting underground services in a developed area comes with a lot of baggage, environmental, fiscal and disruptive. In some places the underground spaces are already pretty full. The cable company chose to go 3 blocks out of their way near my house when they were burying a hard line because they did not want to dig next to 3 telco fibers.

[This message has been edited by gfretwell (edited 06-28-2006).]

High voltage transmission is VERY costly underground.

Hawaii is not big. Its land is very expensive.
They priced bringing power from the western power plants ( fuzzed by Google Earth just north of the western end of H-1 freeway ) to urban Honolulu. ( The city and county of Honolulu covers the entire island.)

The price was a killer: 5 or more times as expensive as conventional overhead lines.

Even with this expensive real estate: it did not pencil out.

In high automobile traffic areas the advantage of underground service overwhelms its expense.

Thusly all highly urbanized areas go underground. It's to stop the nasty consequence of trucks and cars taking out a power pole.

And then when the real estate is fantastically expensive even the high voltage lines run underground.

Superconductors are being field tested -- even now -- for this duty. Thus all prior practice can be overturned. All superconducting schemes are intended for underground power transmission. ( It will require DC for superconditivity -- and inverters close by town.)

In our trade nothing is permanent.

Before we moved in our older hilly neighborhood was retrofitted to underground service. They took a neighborhood vote and it was agreed upon. Each homeowner had to pay out $2000 for the service change.

I have to say it's nice to have an unobstructed view.

It depends on the locale as well. The sand where we live is very easy to dig in (unless it's too wet or too dry, which is 80% of the time).

Go 100 miles west and the ground is either limestone or granite. Very unconducive to underground installations.

It's easy enough to hit something when you drill a hole for a pole. When you trench, you hit sewer lines, water lines, gas lines, pipelines, and (oh yeah) other electric lines. Nothing comes cheap!