Low-frequency measurements of seismic velocity and attenuation in antigorite serpentinite

Emmanuel C. David, Nicolas Brantut, Lars N. Hansen, Ian Jackson

Research output: Contribution to journalArticlepeer-review

Abstract

Laboratory measurements of seismic velocity and attenuation in antigorite serpentinite at a confining pressure of 2 kbar and temperatures up to 550 C (i.e., in the antigorite stability field) provide new results relevant to the interpretation of geophysical data in subduction zones. A polycrystalline antigorite specimen was tested via forced-oscillations at small strain amplitudes and seismic frequencies (mHz-Hz). The shear modulus has a temperature sensitivity, ∂G/∂T, averaging −0.017 GPa K1. Increasing temperature above 500 C results in more intensive shear attenuation (QG1) and associated modulus dispersion, with QG1 increasing monotonically with increasing oscillation period and temperature. This “background” relaxation is adequately captured by a Burgers model for viscoelasticity and possibly results from intergranular mechanisms. Attenuation is higher in antigorite (log10 QG1 ≈ −1.5 at 550 C and 0.01 Hz) than in olivine (log10 QG1 ≪ −2.0 below 800 C), but such contrast does not appear to be strong enough to allow robust identification of antigorite from seismic models of attenuation only.

Original languageEnglish (US)
JournalUnknown Journal
StatePublished - Nov 16 2018
Externally publishedYes

Fingerprint Dive into the research topics of 'Low-frequency measurements of seismic velocity and attenuation in antigorite serpentinite'. Together they form a unique fingerprint.

Cite this