Near-field fault slip of the 2016 Vettore Mw 6.6 earthquake (Central Italy) measured using low-cost GNSS

Abstract

The temporal evolution of slip on surface ruptures during an earthquake is important for assessing fault displacement, defining seismic hazard and for predicting ground motion. However, measurements of near-field surface displacement at high temporal resolution are elusive. We present a novel record of near-field co-seismic displacement, measured with 1-second temporal resolution during the 30th October 2016 Mw 6.6 Vettore earthquake (Central Italy), using low-cost Global Navigation Satellite System (GNSS) receivers located in the footwall and hangingwall of the Mt. Vettore - Mt. Bove fault system, close to new surface ruptures. We observe a clear temporal and spatial link between our near-field record and InSAR, far-field GPS data, regional measurements from the Italian Strong Motion and National Seismic networks, and field measurements of surface ruptures. Comparison of these datasets illustrates that the observed surface ruptures are the propagation of slip from depth on a surface rupturing (i.e. capable) fault array, as a direct and immediate response to the 30th October earthquake. Large near-field displacement ceased within 6–8 seconds of the origin time, implying that shaking induced gravitational processes were not the primary driving mechanism. We demonstrate that low-cost GNSS is an accurate monitoring tool when installed as custom-made, short-baseline networks.

Coseismic Throw Variation Across Along‐Strike Bends on Active Normal Faults: Implications for Displacement Versus Length Scaling of Earthquake Ruptures

“…We suggest that coseismic slip from depth propagated upwards to offset the ground surface, consistent with results measured with Global Navigation Satellite System (GNSS) located in the footwall and hangingwall of the Mt. Vettore fault, which recorded the very rapid formation of the ruptures (2–4 seconds) (Wilkinson et al, ).…”

“…Vettore fault, rerupturing locations that slipped in the 24 August 2016 earthquake and perhaps those on the 26 October (see Figures , , and ; Calderoni et al, ; Cheloni et al, ; Chiaraluce et al, ; Civico et al, ; Falcucci et al, ; Ferrario & Livio, ; Lavecchia et al, ; Mildon et al, ; Pavlides et al, ; Perouse et al, ; Pizzi et al, ; Porreca et al, ; Scognamiglio et al, ; Verdecchia et al, ; Villani, Civico, et al, ; Villani, Pucci, et al, ; Walters et al, ). Meter‐scale offset across surface ruptures was measured with near‐field 1‐Hz global navigation satellite system for the 30 October ruptures, revealing that the ruptures formed within 2–4 s and, before peak ground acceleration, supporting the primary tectonic origin of the ruptures (Wilkinson et al, ; Figure ).…”

22‐kyr‐Long Record of Surface Faulting Along the Source of the 30 October 2016 Earthquake (Central Apennines, Italy), From Integrated Paleoseismic Data Sets

“…This supports the hypothesis that part of the surface faulting along the synthetic zone is missing or widely distributed and was not covered by field surveys. In fact, the near‐field GNSS measurement at this location also belongs to a single synthetic splay (Wilkinson et al, ), while the synthetic fault system likely accommodates a much larger subsidence of its whole hanging wall at a broader scale.…”

“…Vettore slope in the southern portion of the rupture (Brozzetti et al, ; EMERGEO Working Group, , ; Villani, Civico, et al, ; Villani, Pucci, et al, ; Figure ). Measurements of the near‐field coseismic displacement associated with the 30 October 2016 earthquake using low‐cost Global Navigation Satellite System (GNSS) receivers located in the footwall and hanging wall of the VBFS, close to the surface rupture (Wilkinson, ), highlighted the occurrence of surface faulting as a direct effect of the rupture propagation at depth discarding the hypothesis of shaking‐related gravitational collapse, although this cannot be excluded as a secondary effect enhancing at places the ruptures throws.…”

“…Bove fault system (splays POR1, POR2, PRA1, and PRA2) averaged within 100‐m‐long moving windows and projected onto a common N155° trending baseline (from Villani, Pucci, et al, ). The orange square reports the differential coseismic vertical displacement measured by GPS receivers MV01 and MV02 of Wilkinson et al () during the Norcia earthquake. (b, bottom) Paleoseismic throw data from the Hope trench (blue circle = assumed value for the 2016 throw) compared to the coseismic net slip of the 2016 Norcia earthquake along the VET6–VET7 splays (red line); (top) long‐term vertical offset obtained from the total throw in the trench (green triangle; 1.68 ± 0.1), from topographic profiles (orange squares, with error bars shown) and from the inferred low‐resistivity sediment infill in the trench site (green circle).…”