Surface Rupture and Distributed Deformation Revealed by Optical Satellite Imagery: The Intraplate 2016 M_w 6.0 Petermann Ranges Earthquake, Australia

Abstract

High‐resolution optical satellite imagery is used to quantify vertical surface deformation associated with the intraplate 20 May 2016 Mw 6.0 Petermann Ranges earthquake, Northern Territory, Australia. The 21 ± 1‐km‐long NW trending rupture resulted from reverse motion on a northeast dipping fault. Vertical surface offsets of up to 0.7 ± 0.1m distributed across a 0.5‐to‐1‐km‐wide deformation zone are measured using the Iterative Closest Point algorithm to compare preearthquake and postearthquake digital elevation models derived from WorldView imagery. The results are validated by comparison with field‐based observations and interferometric synthetic aperture radar. The pattern of surface uplift is consistent with distributed shear above the propagating tip of a reverse fault, leading to both an emergent fault and folding proximal to the rupture. This study demonstrates the potential for quantifying modest (<1 m) vertical deformation on a reverse fault using optical satellite imagery.

Surface-Rupturing Historical Earthquakes in Australia and Their Environmental Effects: New Insights from Re-Analyses of Observational Data

“…Visible rupture in the Petermann event was highly segmented due to ineffective rupture propagation through sand dunes up to six metres high [73]. Due to this we apply a slightly altered set of criteria to this event, faults are defined where strike of visible rupture and InSAR changes by > 20 • and/or where steps in InSAR and visible rupture are > 1 km ( Figure 10) [75,78].…”

“…Satellite-based imaging of recent scarps (Petermann [75,77,78], Katanning [70], Lake Muir ( [79])) shows permanent distributed displacement of the hanging-wall, and to a lesser degree of the foot-wall that is not captured by these spot-heights and short traverses. Specifically, InSAR imaging shows distributed deformation extending hundreds of metres to kilometres perpendicular to surface scarps [78], and extending along-strike for kilometres beyond the surface rupture detectable in the field [70,78,79]. This is particularly the case for smaller earthquakes (Katanning [70] (Figure 8) and Lake Muir (in review [79])), where the rupture ellipse only partially intersects the surface.…”

Three‐Dimensional Surface Displacements During the 2016 MW 7.8 Kaikōura Earthquake (New Zealand) From Photogrammetry‐Derived Point Clouds

“…In a first for a major earthquake, we use preearthquake and postearthquake aerial photographs to constrain 3-D surface displacements during the 2016 Kaikōura earthquake. Point clouds generated from these aerial photographs bridge the gap between (1) lidar data, which have a very high point density but limited preearthquake spatial coverage in the Kaikōura region ( Figure 1c), and (2) point clouds derived from optical satellite imagery (e.g., Barnhart et al, 2019;Gold et al, 2019), which have good spatial coverage but a higher point spacing than our aerial photograph-derived point clouds (~2 m compared with 0.6 m). We first extract a 3-D coseismic displacement field from the point clouds using the iterative closest point (ICP) algorithm.…”

Resolvability of the Centroid‐Moment‐Tensors for Shallow Seismic Sources and Improvements From Modeling High‐Frequency Waveforms

“…These results are not consistent with what we know about the extreme shallow rupture of this earthquake. Moreover, the optimum mechanism is a reverse fault dipping at 45°, which is inconsistent with the dipping angle of 30°that is observed at the surface (Gold et al, 2019;King et al, 2019a).…”

“…This does not require real earthquake data, and numerical simulations can be performed in a purely synthetic setup. However, we construct our synthetic study around the source area of the 20 May 2016, Petermann Ranges, central Australia earthquake (Figure 2), which has been extensively studied (Gold et al, 2019;Hejrani & Tkalčić, 2019;King et al, 2019aKing et al, , 2019b. The moderate-to-high magnitude of this event (M w 5.9) and the fact that we possess a range of 3-D and 1-D Earth models to calculate the synthetics for 21 seismic stations surrounding the source region make the setting ideal to corroborate our results.…”