Low friction along the high slip patch of the 2011 Mw 9.0 Tohoku-Oki earthquake required from the wedge structure and extensional splay faults

N. Cubas, J. P. Avouac, Y. M. Leroy, A. Pons

Research output: Contribution to journalArticle

37 Citations (Scopus)

Abstract

We analyze the mechanical properties needed to account for the large shallow slip during the 2011 Tohoku-Oki earthquake and the activation of landward normal faulting within the forearc. We show that the morphology and internal structure of the forearc follows closely the prediction of the critical Coulomb wedge in horizontal compression, implying a high internal pore pressure ratio (λ=0.7+0.14/-0.48) and a low effective basal friction (μbeff=0.14+0.18/-0.04). We then show that the activation of the normal fault requires a lower effective basal friction beneath the outer wedge than beneath the inner wedge (μouter≤0.015), possibly due to transient dynamic weakening associated to the seismic rupture. Forearc normal faults could be considered as evidence for very efficient dynamic weakening along the megathrust and typify megathrust with high tsunamigenic potential. Key Points Long-term high pore pressure and low effective friction along the Megathrust Very efficient dynamic weakening observed along high slip patch Splay faults can be used to typify Megathrust with high tsunamigenic potential.

Original languageEnglish
Pages (from-to)4231-4237
Number of pages7
JournalGeophysical Research Letters
Volume40
Issue number16
DOIs
Publication statusPublished - 28 Aug 2013

Keywords

  • Coulomb wedge
  • dynamic weakening
  • frictional properties
  • megathrust
  • splay fault
  • Tohoku-Oki earthquake

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