Last week's natural and man-made disasters in the form of deadly tornadoes and exploding oil rigs has resulted in significant exposure for insurers and reinsurers, according to two different reports from Guy Carpenter.

Yesterday, the company reported that an explosion and large fire on an oil rig in the Gulf of Mexico on April 20 left 11 workers dead and 17 others injured. Reports said the rig, which is owned by Transocean Ltd, was under contract to the oil company BP at a cost of $533,000 a day, and was conducting exploratory drilling. The rig eventually sunk on April 22, and has resulted in a leak of 1,000 barrels of oil per day into the Gulf of Mexico. The rig was located around 42 miles offshore Venice, La.

In a release dated April 26, Transocean said that the rig, named Deepwater Horizon, "had a value of $560 million and was insured for total loss coverage and for wreck removal, to the extent removal can be carried out and is required."