DOI: 10.1016/j.epsl.2018.09.005
Scopus记录号: 2-s2.0-85053480957
论文题名: P-wave attenuation structure of the Lau back-arc basin and implications for mantle wedge processes
作者: Wei S.S. ; Wiens D.A.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2018
卷: 502 起始页码: 187
结束页码: 199
语种: 英语
英文关键词: Lau back-arc basin
; mantle wedge
; P-wave attenuation
; partial melting
; Tonga subduction zone
Scopus关键词: Earthquakes
; Flow patterns
; Grain boundary sliding
; Melting
; Lau back-arc basins
; Mantle wedge
; P waves
; Partial melting
; Subduction zones
; Seismic waves
; backarc basin
; mantle structure
; P-wave
; partial melting
; seismic attenuation
; seismic velocity
; seismograph
; spreading center
; subduction zone
; three-dimensional modeling
; wave attenuation
; Australia
; Lau Basin
; Pacific Ocean
英文摘要: We image 3-D seismic P-wave attenuation structure of the Tonga subduction zone and the Lau back-arc basin using local earthquake waveforms recorded by land and ocean bottom seismographs of the 2009–2010 Lau Spreading Center Imaging project. The amplitude spectra of P waves from local earthquakes are inverted for the path-average attenuation operator (t⁎), with a variety of frequency-dependence exponent values (α). Analysis shows that the data are best fit by the assumption of a weak frequency dependence (α≈0.3), consistent with laboratory results modeled as the effects of grain boundary sliding. The t⁎ measurements are inverted for a 3-D tomographic QP −1 model. The results show high P-wave attenuation within the upper 100 km of the back-arc mantle, with a sharp boundary at the Tofua arc between high attenuation sub-arc mantle and the low attenuation fore-arc. Perhaps the highest P-wave attenuation (QP −1≈0.036 or QP≈28) known in the mantle occurs at 20–60 km depth beneath the back-arc spreading centers. High attenuation anomalies form an inclined zone dipping from the spreading centers to the west away from the slab, indicating abnormally high temperature and the existence of hydrous partial melt. These observations suggest that hot materials supplied from the Australian mantle upwell along with the mantle wedge flow pattern, triggering extensive decompression melting near the back-arc spreading centers. The along-strike variation of P-wave attenuation is different from that of SV-velocity, possibly implying the different effects of partial melt on seismic attenuation and velocity. © 2018 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/109645
Appears in Collections: 影响、适应和脆弱性 气候变化事实与影响
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作者单位: Department of Earth and Environmental Sciences, Michigan State University, East Lansing, MI, United States; Department of Earth and Planetary Sciences, Washington University, St. Louis, MO, United States
Recommended Citation:
Wei S.S.,Wiens D.A.. P-wave attenuation structure of the Lau back-arc basin and implications for mantle wedge processes[J]. Earth and Planetary Science Letters,2018-01-01,502