Natural catastrophes cost the insurance industry $7.9bn in 1996 - the lowest amount for eight years. A new report, however, suggests that future costs could rise dramatically.

Hurricanes have caused $355bn worth of damage on the US mainland since 1925. Chris Lansea, a researcher at the National Oceanic and Atmospheric Administration, reported the results into his study of a century of hurricanes to a conference in Miami, and the conclusions give grounds for concern.

Calculating each year's damage at today's prices, Lansea estimates that the last 70 years have seen an average annual cost of $5bn in hurricane damage. "That's what we should expect, about $5bn a year. That's a lot of damage," he said. His most startling figures, however, come from extrapolating the damage caused by earlier hurricanes to the glamorous, expensively furnished, microwave-rich, overpopulated Miami sea front of today. By those standards, an unnamed storm of 1926 would have caused $74.7bn damage.

That takes first place in Lansea's new league table of disastrous hurricanes, relegating Hurricane Andrew, which caused $34.2bn damage in 1992, to second place. Hurricane Hugo, which cost South Carolina $9.7bn in 1989, is down from second place to 11th.