Analyzing rates of fault creep along passive margin growth faults in coastal Louisiana using Airborne-LiDAR

Abstract:

Subsidence along the Gulf of Mexico passive margin exacerbates the challenges of sea-level rise, particularly along the Mississippi delta region. In the Mississippi delta area, subsidence is driven by compaction of compressible sediments, glacial isostatic adjustment, groundwater extraction, and growth faulting. Extensive seismic surveying, coring, and earlier LiDAR surveys show slip along coastal detachment faults over the past 10,000 years, but the rate of growth fault slip remains poorly quantified. Our objective is to use multidate airborne LiDAR surveys spanning 2002 to 2018 to determine rates of creep along two coast-parallel detachment faults: Denham Springs and Baton Rouge faults. With this information we will quantify the contribution of fault creep to subsidence and to evaluate the spatial variability of displacements. The datasets were captured in 2002, 2017 and 2018 and each one has a different point spacing (4 meters, 0.7 meters and 0.33 meters respectively). We are using three different approaches to estimate rates of displacement and their spatial variability: 1) point by point comparison of returns on stable and less scattered zones in the datasets, 2) Iterative Closest Point (ICP) algorithm to perform 3D differencing and 3) Geomorphic Change Detection software. The point by point comparison provides estimates of the uncertainties in the differential LiDAR images. Also, we are using InSAR information from the satellite Sentinel-1 to compare with our LiDAR results.