LaDiCaoz and LiDARimager—MATLAB GUIs for LiDAR data handling and lateral displacement measurement

摘要

Light detection and ranging (LiDAR), high-resolution topographic data sets enable remote identification of submeter-scale geomorphic features and have proven very valuable in geologic, paleoseismic, and geomorphologic investigations. They are also useful for studies of hydrology, timber evaluation, vegetation dynamics, coastal monitoring, hill-slope processes, or civil engineering. One application for LiDAR data is the measurement of tectonically displaced geomorphic markers to reconstruct paleoearthquake slip distributionscurrently a cornerstone in the formulation of earthquake recurrence models and the understanding of seismic fault behavior. With this publication we provide two MATLAB-based graphical user interfaces (GUIs) and corresponding tutorials: LiDARimagera tool for LiDAR data handling and visualization (e.g., data cropping, generation of map- and oblique-view plots of various digital elevation model [DEM] derivatives, storable as *.jpg or *.kmz files); and LaDiCaoza tool to determine lateral displacements of offset sublinear geomorphic features such as stream channels or alluvial fan edges. While application of LaDiCaoz is closely linked to tectonogeomorphic studies, LiDARimager may find application in a wide range of studies that utilize LiDAR data visualizations. A key feature of LaDiCaoz, not available in standard geographic information system (GIS) packages, is DEM slicing and (laterally) back slipping for visual offset reconstruction assessment, improving measurement accuracy and precision. Comparison of offset measurements, made by different individuals, showed good measurement repeatability with LaDiCaoz for morphologically simple channels. Offset estimates began to vary distinctly for morphologically more complex features, attributed to different assumptions of pre-earthquake morphology and underlining the importance of a sound understanding of pre-earthquake site morphology for meaningful offset measurements.