Risk analysis for hurricane-wave induced submarine mudslides

Abstract

Hurricane waves in the Gulf of Mexico can trigger mudslides in the relatively weak clays in the offshore Mississippi Delta region. Mudslides can cause extensive damage to the infrastructure that supports offshore oil and gas production, including platforms and pipelines. This paper presents a method for assessing the probability and risk for future mudslides in the Delta as a function of the possible sizes of waves, bathymetry, and shear strengths of sea floor soils. The method has been calibrated to the extent possible using historical information. The method is transparent and can readily include either generic or site-specific information about soil properties and wave characteristics. The method is applied regionally to develop maps depicting the risk to locations and to pipelines. Return periods for mudslides vary significantly across the Delta, with values less than 30 years in the shallowest water and values greater than 1, 000 years in the deepest water. Wave period, in addition to wave height, is an important factor in mudslide vulnerability. Mudslides are localized features, on the order of several thousand feet in lateral extent and about 50 to 150 feet deep. The areal extent and depth of mudslides are related to the lengths and widths of the storm waves that cause them. © Springer Science + Business Media B.V. 2010.