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Uncertainty in strain-rate from field measurements of the geometry, rates and kinematics of active normal faults: Implications for seismic hazard assessment

Sgambato, C; Faure Walker, JP; Roberts, GP; (2020) Uncertainty in strain-rate from field measurements of the geometry, rates and kinematics of active normal faults: Implications for seismic hazard assessment. Journal of Structural Geology , 131 , Article 103934. 10.1016/j.jsg.2019.103934. Green open access

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Abstract

Multiple measurements of the geometry, kinematics and rates of slip across the Auletta fault (Campania, Italy) are presented, and we use these to determine: (1) the spatial resolution of field measurements needed to accurately calculate a representative strain-rate; (2) what aspects of the geometry and kinematics would introduce uncertainty with regard to the strain-rate if not measured in the field. We find that the magnitude of the post last-glacial maximum throw across the fault varies along strike. If such variations are unnoticed, different values for a representative strain-rate, hence different results in seismic hazard calculations, would be produced. To demonstrate this, we progressively degrade our dataset, calculating the implied strain-rate at each step. Excluding measurements can alter strain-rate results beyond 1σ uncertainty, thus we urge caution when using only one measurement of slip-rate for calculating hazard. We investigate the effect of approximating the throw profile along the fault with boxcar and triangular distributions and show that this can underestimate or overestimate the strain-rate, with results in the range of 72–237% of our most detailed strain-rate calculation. We discuss how improved understanding of the potential implied errors in strain-rate calculations from field structural data should be implemented in seismic hazard calculations.

Type: Article
Title: Uncertainty in strain-rate from field measurements of the geometry, rates and kinematics of active normal faults: Implications for seismic hazard assessment
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.jsg.2019.103934
Publisher version: https://doi.org/10.1016/j.jsg.2019.103934
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Active normal fault, Fault geometry, Strain-rate, Seismic hazard, Italy
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Earth Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Inst for Risk and Disaster Reduction
URI: https://discovery.ucl.ac.uk/id/eprint/10087315
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