Post-glacial Sediment Load and Subsidence in Coastal Louisiana

Abstract

Sea level rise in the Gulf of Mexico has occurred at a rate of 1.8-2.2 mm/yr during the 20th century, or nearly the same as observed globally due to combined steric and water mass changes. Tide gauges in coastal Louisiana, however, record a substantially larger rate of rise and while a number of causal mechanisms may be responsible, their specific contribution is poorly understood. Using a realistic viscoelastic Earth model, detailed geologic parameters for south Louisiana and new GPS data, we demonstrate that Holocene sedimentary loading in the Gulf and Mississippi River delta is capable of contributing to 1-8 mm/yr of subsidence over areas of 30-0.75 x 10(exp 3) km(exp 2)