Applications of airborne and terrestrial laser scanning to paleoseismology

David E. Haddad, Sinan O. Akciz, Ramon R. Arrowsmith, Dallas D. Rhodes, John Oldow, Olaf Zielke, Nathan A. Toke, April Haddad, Juergen Mauer, & Prabin Shilpakar

Published 2012, SCEC Contribution #1631

Paleoseismic investigations aim to document
past earthquake characteristics such
as rupture location, frequency, distribution
of slip, and ground shaking intensity—critical
parameters for improved understanding
of earthquake processes and refined
earthquake forecasts. These investigations
increasingly rely on high-resolution (<1 m)
digital elevation models (DEMs) to measure
earthquake-related ground deformation and
perform process-oriented analyses. Three
case studies demonstrate airborne and terrestrial
laser scanning (ALS and TLS) for
paleoseismic research. Case 1 illustrates
rapid production of accurate, high-resolution,
and georeferenced three-dimensional
(3D) orthophotographs of stratigraphic and
fault relationships in trench exposures. TLS
scans reduced the preparation time of the
trench and provided 3D visualization and
reconstruction of strata, contacts, and permanent
digital archival of the trench. Case 2
illustrates quantifi cation of fault scarp degradation
rates using repeat topographic surveys.
The topographic surveys of the scarps
formed in the 1992 Landers (California)
earthquake documented the centimeter-scale
erosional landforms developed by repeated
winter storm-driven erosion, particularly in
narrow channels crossing the surface rupture.
Vertical and headward incision rates
of channels were as much as ~6.25 cm/yr
and ~62.5 cm/yr, respectively. Case 3 illustrates
characterization of the 3D shape and
geomorphic setting of precariously balanced
rocks (PBRs) that serve as negative indicators
for strong ground motions. Landscape
morphometry computed from ALS-derived
DEMs showed that PBRs are preserved on
hillslope angles between 10° and 40° and
contributing areas (per unit contour length)
between 5 and 30 m2/m. This situation refi nes
interpretations of PBR exhumation rates and
thus their effectiveness as paleoseismometers.
Given that earthquakes disrupt Earth’s
surface at centimeter to meter scales and that
depositional and erosional responses typically
operate on similar scales, ALS and TLS
provide the absolute measurement capability
suffi cient to characterize these changes
in challenging geometric arrangements, and
thus demonstrate their value as effective analytical
tools in paleoseismology.

Haddad, D. E., Akciz, S. O., Arrowsmith, R. R., Rhodes, D. D., Oldow, J., Zielke, O., Toke, N. A., Haddad, A., Mauer, J., & Shilpakar, P. (2012). Applications of airborne and terrestrial laser scanning to paleoseismology. Geosphere, 8(4), 771-786. doi: 10.1130/GES00701.1.