Thin and intermittent ultralow-velocity zones

Sebastian Rost, Edward Garnero, Wolfgang Stefan

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

An area of the core-mantle boundary to the east of Australia is investigated for the existence of ultralow-velocity zones (ULVZs). High-frequency recordings of deep Vanuatu and Tonga-Fiji earthquakes are studied from the small-aperture Warramunga Seismic Array in central Australia. The Tonga-Fiji data were used in a previous ULVZ study, while earthquakes from the Vanuatu subduction zone were newly collected for this study. Core-reflected ScP waves were analyzed, which possess observable precursory and postcursory arrivals in the presence of ULVZ structure. We apply a total variation deconvolution algorithm to our data, which significantly sharpens observed signals, hence, increasing our vertical resolution and therefore allowing us to detect thinner ULVZs than previously possible. The minimum ULVZ thickness detection threshold is approximately 2-3 km with this method. This data set samples a spot at the boundary of the large low shear velocity province beneath the Pacific. The new analysis provides evidence for a 5-6 km thick ULVZ to the north of a previously detected 8.5 km thick ULVZ. A second sampled region shows evidence for an even thinner ULVZ structure, with thicknesses of ∼3 km. These findings are largely consistent with the hypothesis that ULVZs are most likely to be found along the inside margin of large low shear velocity regions that have been attributed to dense, chemically distinct material.

Original languageEnglish (US)
Article numberB06312
JournalJournal of Geophysical Research: Solid Earth
Volume115
Issue number6
DOIs
StatePublished - 2010

Fingerprint

Earthquakes
earthquakes
shear
core-mantle boundary
earthquake
reflected waves
Deconvolution
deconvolution
subduction zone
arrivals
margins
apertures
recording
thresholds
method
province
detection
analysis
material

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science

Cite this

Thin and intermittent ultralow-velocity zones. / Rost, Sebastian; Garnero, Edward; Stefan, Wolfgang.

In: Journal of Geophysical Research: Solid Earth, Vol. 115, No. 6, B06312, 2010.

Research output: Contribution to journalArticle

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