Bridging spatiotemporal scales of fault growth during continental extension

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Authors

Sophie Pan , John Naliboff, Rebecca E. Bell, Chris Jackson

Abstract

Continental extension is accommodated by the development of kilometre-scale normal faults, which grow by accumulating metre-scale earthquake slip over millions of years. Reconstructing the entire lifespan of a fault remains challenging due to a lack of observational data with spatiotemporal scales that span the relatively short-term earthquake cycle, and the longer-term paleoseismic record. Using 3D numerical simulations of continental extension and novel fault extraction, we examine key factors controlling the growth of large faults over 10^4-10^6 yrs. Modelled faults quantitatively show key geometric and kinematic similarities with natural fault populations, with early faults (<100 kyrs from initiation) exhibiting scaling ratios consistent with those characterising individual earthquake ruptures. While finite lengths are rapidly established (<100 kyrs), active deformation is transient, migrating both along- and across-strike. Competing stress interactions determine the active strain distribution, which oscillate locally between localised and distributed endmembers. Modelling suggests that far-field dynamic triggering can drive rupture propagation, producing recurring, large through-going slip. Our findings demonstrate that fault growth and the related occurrence of earthquakes is more complex than that currently inferred from observing displacement patterns on now-inactive structures, which only provide a spatial- and time-averaged picture of fault kinematics and related geohazard.

DOI

https://doi.org/10.31223/X5DG7M

Subjects

Earth Sciences, Geology, Geophysics and Seismology, Other Earth Sciences, Physical Sciences and Mathematics, Tectonics and Structure

Keywords

seismic, rifts, faults, networks, normal, numerical, models, transient, timescales

Dates

Published: 2021-04-21 11:52

Last Updated: 2021-06-13 06:52

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License

CC BY Attribution 4.0 International

Additional Metadata

Data Availability (Reason not available):
We do not have the publicly available location yet but will update

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