High-frequency ambient noise tomography of southeast Australia

New constraints on Tasmania's tectonic past

M. K. Young, N. Rawlinson, P. Arroucau, A. M. Reading, H. Tkalcic

Research output: Contribution to journalArticle

43 Citations (Scopus)

Abstract

The island of Tasmania, at the southeast tip of Australia, is an ideal natural laboratory for ambient noise tomography, as the surrounding oceans provide an energetic and relatively even distribution of noise sources. We extract Rayleigh wave dispersion curves from the continuous records of 104 stations with ∼15 km separation. Unlike most passive experiments of this type, which observe very little coherent noise below a 5 s period, we clearly detect energy at periods as short as 1 s, thanks largely to the close proximity of oceanic microseisms on all sides. The main structural elements of the eastern and northern Tasmanian crust are revealed by inverting the dispersion curves (between 1 and 12 s period) for both group and phase velocity maps. Of particular significance is a pronounced band of low velocity, observed across all periods, that underlies the Tamar River Valley and continues south until dissipating in southeast Tasmania. Together with evidence from combined active source and teleseismic tomography and heat flow data, we interpret this region as a diffuse zone of strong deformation associated with the mid-Paleozoic accretion of oceanic crust along the eastern margin of Proterozoic Tasmania, which has important implications for the evolution of the Tasman Orogen of eastern Australia. In the northwest, a narrower low-velocity anomaly is seen in the vicinity of the Arthur Lineament, which may be attributed to local sediments and strong deformation and folding associated with the final phases of the Tyennan Orogeny.
Original languageEnglish
Article numberL13313
Number of pages6
JournalGeophysical Research Letters
Volume38
Issue number13
DOIs
Publication statusPublished - Jul 2011

Fingerprint

Tasmania
ambient noise
tomography
tectonics
wave dispersion
low speed
crusts
phase velocity
Rayleigh wave
lineament
microseisms
orogeny
heat flow
oceanic crust
folding
Proterozoic
energetics
Paleozoic
accretion
Rayleigh waves

Keywords

  • Tasmania
  • ambient noise
  • group velocity
  • tomography

Cite this

High-frequency ambient noise tomography of southeast Australia : New constraints on Tasmania's tectonic past. / Young, M. K.; Rawlinson, N.; Arroucau, P.; Reading, A. M.; Tkalcic, H.

In: Geophysical Research Letters, Vol. 38, No. 13, L13313, 07.2011.

Research output: Contribution to journalArticle

Young, M. K. ; Rawlinson, N. ; Arroucau, P. ; Reading, A. M. ; Tkalcic, H. / High-frequency ambient noise tomography of southeast Australia : New constraints on Tasmania's tectonic past. In: Geophysical Research Letters. 2011 ; Vol. 38, No. 13.
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