Orogen-scale uplift in the central Italian Apennines drives episodic behaviour of earthquake faults

Cowie, P.A.; Phillips, R.J.; Roberts, G.P.; McCaffrey, K.; Zijerveld, L.J.J.; Gregory, L.C.; Faure Walker, J.; Wedmore, L.; Dunai, T.J.; Binnie, S.A.; Freeman, S.P.H.T.; Wilcken, K.; Shanks, RP.; Huismans, R.S.; Papanikolaou, I.; Michetti, A.M.; Wilkinson, M.

Abstract

Many areas of the Earth’s crust deform by distributed extensional faulting and complex fault interactions are often observed. Geodetic data generally indicate a simpler picture of continuum deformation over decades but relating this behaviour to earthquake occurrence over centuries, given numerous potentially active faults, remains a global problem in hazard assessment. We address this challenge for an array of seismogenic faults in the central Italian Apennines, where crustal extension and devastating earthquakes occur in response to regional surface uplift. We constrain fault slip-rates since ~18 ka using variations in cosmogenic 36Cl measured on bedrock scarps, mapped using LiDAR and ground penetrating radar, and compare these rates to those inferred from geodesy. The 36Cl data reveal that individual faults typically accumulate meters of displacement relatively rapidly over several thousand years, separated by similar length time intervals when slip-rates are much lower, and activity shifts between faults across strike. Our rates agree with continuum deformation rates when averaged over long spatial or temporal scales (104 yr; 102 km) but over shorter timescales most of the deformation may be accommodated by <30% of the across-strike fault array. We attribute the shifts in activity to temporal variations in the mechanical work of faulting.

Citation

Cowie, P., Phillips, R., Roberts, G., McCaffrey, K., Zijerveld, L., Gregory, L., …Wilkinson, M. (2017). Orogen-scale uplift in the central Italian Apennines drives episodic behaviour of earthquake faults. Scientific Reports, 7, Article 44858. https://doi.org/10.1038/srep44858

• Journal Article Type: Article
• Acceptance Date: Feb 20, 2017
• Online Publication Date: Mar 21, 2017
• Publication Date: Mar 21, 2017
• Deposit Date: Feb 21, 2017
• Publicly Available Date: Feb 21, 2017
• Journal: Scientific Reports
• Publisher: Nature Research
• Peer Reviewed: Peer Reviewed
• Volume: 7
• Article Number: 44858
• DOI: https://doi.org/10.1038/srep44858
• Public URL: https://durham-repository.worktribe.com/output/1364744