Partitioned Off‐Fault Deformation in the 2016 Norcia Earthquake Captured by Differential Terrestrial Laser Scanning

Field measurements of coseismic fault slip often differ from surface slip models derived from satellite geodesy. Quantifying these differences is challenging as many geodetic techniques inadequately image near‐fault deformation. We use an iterative closest point algorithm to difference preearthquake and postearthquake terrestrial laser scanning point clouds to reveal centimeter‐scale patterns of surface deformation caused by shallow fault slip in the 2016 Mw 6.6 Norcia (Central Italy) earthquake. Terrestrial laser scanning offsets are constant along the fault and match average field measurements. Eighty‐four percent of vertical displacement occurs on a discrete fault zone, with 16% of deformation distributed across a narrow zone <4 m wide. In contrast, horizontal deformation is distributed over an 8‐m‐wide zone with approximately 50% of extension accommodated as off‐fault deformation (OFD). The centimeter‐scale observation of deformation shows that horizontal and vertical coseismic OFD is partitioned—in this case, OFD is dominated by horizontal deformation.