LiDAR and InSAR analysis of deformation in the Krafla rift zone, NE Iceland

• Main Author: Bramham, Emma Kristy
• Format: Thesis
• Language: English
• Published: University of Leeds 2014
• Subjects: Krafla; Iceland
• Online Access: https://etheses.whiterose.ac.uk/7826/; https://etheses.whiterose.ac.uk/7826/1/emma_bramham_PHD_thesis.pdf

Current models of fault growth examine the relationship of fault length (L) to vertical displacement (D) where the faults exhibit the classic fault shape of gradually increasing vertical displacement from zero at the fault tips to a maximum displacement (Dmax) at the middle of the fault. These models cannot adequately explain displacement length observations at the Krafla fissure swarm, in Iceland's northern volcanic zone, where I observe that many of the faults with significant vertical displacements still retain fissure-like features, with no vertical displacement, along portions of their lengths. I have created a high resolution digital elevation model (DEM) of the Krafla region using airborne LiDAR and measured the displacement/length profiles of 775 faults, with lengths ranging from 10s to 1000s of metres. I have categorised the faults based on the proportion of the profile that was still fissure-like. Fully-developed faults (no fissure-like regions) were further grouped into those with profiles that had a flattened appearance (large regions of constant vertical displacment), those with a classical fault shape and those that show regions of fault linkage. I measured the Dmax/L ratio of each identifiable original fault within the linked fault profiles, evidencing that the majority of the original faults had reached the maximum D/L prior to linkage. I suggest that a fault can most easily accommodate stress by displacing regions that are still fissure-like, and that a fault would be more likely to accommodate stress by linkage once it has reached the maximum displacement for its fault length. My results demonstrate that there is a pattern of growth from fissure to fault in the Dmax/L ratio of the categorised faults and propose a model for this growth. I suggest it is possible to better understand how faults grow in their earliest stages of development and that the proposed model can be incorporated as an early stage of fault growth for current models which only model behaviour of a fault once it has acquired ...