Don't assume that your homeowner's insurance automatically covers nature's most devastating disasters. Depending on where you live, you may have to buy additional insurance riders for flood, hurricane or earthquake insurance.

Homeowner's policies never include flood coverage, which most people don't realize until it's too late.

You can get coverage for as low as $80 through the National Flood Insurance Program (a Federal Emergency Management Agency (FEMA)-sponsored program), provided your community belongs to the National Flood Insurance Program.

You'll be required to get flood coverage if you buy a home in a "flood hazard" area using a federally backed mortgage loan. However, if you live in one of the FEMA-designated highest-risk zones, you may not be able to get flood coverage at all. It'll be your risk.

Earthquake coverage varies state by state, so you can't assume that your all-purpose homeowner's policy covers earthquakes.

In some states you can add earthquake coverage to your existing homeowner's policy, while in others - such as California - you must purchase an additional policy altogether.

The premiums may seem outrageous to you, but if you live in an earthquake-prone area, it's pretty risky to "go naked," as it's called if you don't have the coverage. Any damage that exceeds the deductible is likely to require major structural repairs. The deductibles in many earthquake-prone areas can be as high as $10,000 or 10 percent of the damage, whichever is higher.

If you don't live in a hurricane-prone area, most "broad-purpose" homeowners' policies should include hurricane coverage.

In vulnerable areas, hurricanes are not covered automatically and you'll need an additional policy. The premium may be high but it's worth the cost.