AIR estimates include wind and storm-surge damage
Hurricane Isaac could cause insured losses of between $700m and $2bn, according to estimates from risk modelling firm AIR Worldwide.
The estimates include wind and storm-surge damage to onshore residential, commercial and industrial properties and their contents, motor vehicles, additional living expenses for residential properties and business interruption for commercial properties.
Isaac hit the US Gulf Coast as a Category 1 Hurricane on the Saffir-Simpson scale on both Tuesday and Wednesday. The first landfall hit Plaquemines Parish. Louisiana on Tuesday and the second just west of Port Fourchon, Louisiana on Wednesday.
AIR principal scientist Tim Doggett said: “Inland flooding from continuing precipitation remains a risk and isolated tornadoes may still be spawned by the storm. Total rainfall accumulations of 7 to 14 inches are expected, with isolated amounts up to 25 inches.”
Damage reports have mostly been focused on the flooding caused by Isaac’s precipitation shield and slow movement. Nearly eight inches of rain were reported at the New Orleans International Airport yesterday. Much of the worst flooding occurred in Plaquemines Parish, Louisiana, where a combination of storm surge and rainfall caused water to top the earthen levees.
Wind damage has been less extensively reported. “However, Isaac’s slow forward speed and refusal to dissipate will exacerbate wind damage,” Doggett said. “As the winds persist, roof fasteners and connections can become fatigued and overloaded causing additional damage, and the possibility of damage from flying building debris persists. It should also be noted that with soils heavily saturated by rain, trees can be downed by much lower wind speeds than would otherwise be necessary.”
Downed power lines, trees and other infrastructure are being reported over much of southern Louisiana and Mississippi. Some structural damage is being reported in New Orleans and the surrounding area, mostly limited to roof damage and to non-structural elements such as awnings, signage, and trailers.
AIR does not expect significant physical damage to offshore oil rigs and gas platforms either from wind or waves. Furthermore, as a result of the Gulf hurricanes of 2005 (Katrina, Rita and Wilma), Hurricane Gustav in 2008, and the Deepwater Horizon disaster of 2010, business interruption is a much rarer coverage than in years past. Therefore, AIR does not expect significant insured losses to offshore assets in the Gulf of Mexico as a result of Isaac.
