3-D visualisation of palaeoseismic trench stratigraphy and trench logging using terrestrial remote sensing and GPR – a multiparametric interpretation
Two normal faults on the island of Crete and mainland Greece were studied to test an innovative workflow with the goal of obtaining a more objective palaeoseismic trench log, and a 3-D view of the sedimentary architecture within the trench walls. Sedimentary feature geometries in palaeoseismic trenc...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-03-01
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| Series: | Solid Earth |
| Online Access: | http://www.solid-earth.net/7/323/2016/se-7-323-2016.pdf |
| Summary: | Two normal faults on the island of Crete and mainland Greece were
studied to test an innovative workflow with the goal of obtaining a more
objective palaeoseismic trench log, and a 3-D view of the sedimentary
architecture within the trench walls. Sedimentary feature geometries in
palaeoseismic trenches are related to palaeoearthquake magnitudes which are
used in seismic hazard assessments. If the geometry of these sedimentary
features can be more representatively measured, seismic hazard assessments
can be improved. In this study more representative measurements of
sedimentary features are achieved by combining classical palaeoseismic
trenching techniques with multispectral approaches. A conventional trench log
was firstly compared to results of ISO (iterative self-organising) cluster analysis of a true colour
photomosaic representing the spectrum of visible light. Photomosaic
acquisition disadvantages (e.g. illumination) were addressed by complementing
the data set with active near-infrared backscatter signal image from t-LiDAR
measurements. The multispectral analysis shows that distinct layers can be
identified and it compares well with the conventional trench log. According
to this, a distinction of adjacent stratigraphic units was enabled by their
particular multispectral composition signature. Based on the trench log, a
3-D interpretation of attached 2-D ground-penetrating radar (GPR) profiles collected on the vertical
trench wall was then possible. This is highly beneficial for measuring
representative layer thicknesses, displacements, and geometries at depth
within the trench wall. Thus, misinterpretation due to cutting effects is
minimised. This manuscript combines multiparametric approaches and shows
(i) how a 3-D visualisation of palaeoseismic trench stratigraphy and logging
can be accomplished by combining t-LiDAR and GPR techniques, and (ii) how a
multispectral digital analysis can offer additional advantages to interpret
palaeoseismic and stratigraphic data. The multispectral data sets are stored
allowing unbiased input for future (re)investigations. |
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| ISSN: | 1869-9510 1869-9529 |