Deformation of marine terraces in coastal Humboldt County, California: an evaluation using GIS-based analysis of LiDAR imagery

Forming at sea level, uplifted wave-cut platforms serve as long-term geodetic markers. The spatial distribution and elevation of marine terrace sequences offer insight to regional active tectonics. Using LiDAR imagery embedded within a geospatial information system (GIS), we employ a surface classification model (SCM) developed by Bowels and Cowgill (2012) that identifies uplifted marine terraces on the basis of their micro topographical characteristics, low slope and low roughness. The LiDAR data sets were compiled utilizing several public and private sources to cover a large portion of the Humboldt County (northern California) coastline extending from Big Lagoon south to Table Bluff. We supplement LiDAR-derived elevations with elevations derived from kinematic GPS. We test the applicability of the SCM approach to identifying deformed marine terraces, and we also use other geomorphic analyses, including longitudinal profiles and distribution of knickpoints, to assess tectonic evolution and rates of landscape change along the central Humboldt County coastal region. Uplifted marine terraces record the regional patterns of uplift; these patterns both record the development of several north-northwest trending thrust faults, anticlines and synclines and chronicle Quaternary tectonic deformation and erosional histories.