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| Titel |
Measuring fracture energy under coseismic conditions |
| VerfasserIn |
Stefan Nielsen, Elena Spagnuolo, Marie Violay, Steven Smith, Pier-Giorgio Scarlato, Gianni Romeo, Fabio Di Felice, Giulio Di Toro |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250082052
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| Zusammenfassung |
| Experiments performed on rocks at deformation conditions typical of seismic slip, show an
extremely low friction coefficient, the activation of lubrication processes and a power-law
strength decay from a peak value to a residual, steady-state value. The weakening curve has
an initially very abrupt decay which can be approximated by a power-law. The resulting
experimental fracture energy (defined, for a given slip amount u, as the integral between the
frictional curve and the minimum frictional level reached Ïăf(u)) scales on most
of the slip range as GÂ - Â uα, a power-law in some aspects in agreement with
the seismological estimates of G′- Â u1.28 proposed by Abercrombie and Rice
(2005). The values of G and G′ are comparable for slips of about u = 1cm (G - 104
J/m2). Both gradually increase with slip up to about 106 J/m2, however, it appears
that fracture energy G′ is slightly larger than G in the range of slip 0.1 < u < 10.
The effective G′ observed at the seismological scale should implicitly incorporate
energy sinks other than frictional dissipation alone, which we discuss (anelastic
damage due to high off-fault dynamic stress close to the rupture tip; dissipation during
slip-localizing process within fault gouge of finite thickness; strain accomodating
fault roughness at different scales). Since G′ is obtained by estimating the amount
of dissipation with respect to strain energy and radiated energy, it will implicitly
incorporate the sum of all dissipative processes due to rupture propagation and fault slip.
From the comparison of G obtained in the lab and in earthquakes, it appears that
friction alone explains most of the dissipation, except maybe at the larger magnitudes. |
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