Partitioned postseismic deformation associated with the 2009 Mw 6.3 L'Aquila earthquake surface rupture measured using a terrestrial laser scanner

Using 3D terrestrial laser scan (TLS) technology, we have recorded postseismic
deformation on and adjacent to the surface rupture formed during the 6th April
2009 L’Aquila normal faulting earthquake (Mw 6.3). Using surface modeling
techniques and repeated surveys 8 – 124 days after the earthquake, we have
produced a 4D dataset of postseismic deformation across a 3 x 65 m area at high
horizontal spatial resolution. We detected millimetre-scale movements
partitioned between discrete surface rupture slip and development of a
hangingwall syncline over 10’s of meters. We interpret the results as the signal of
shallow afterslip in the fault zone. We find 52% of the total postseismic
hangingwall vertical motion occurs as deformation within 30 m of the surface
rupture. The total postseismic vertical motions are approximately 50% that of
the coseismic. We highlight the importance of quantifying partitioned postseismic contributions when applying empirical slip-magnitude datasets to
infer palaeoearthquake magnitudes.