气候变化领域集成服务门户(CCPortal): High Bulk and Shear Attenuation Due to Partial Melt in the Tonga-Lau Back-arc Mantle

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DOI	10.1029/2019JB017527
	High Bulk and Shear Attenuation Due to Partial Melt in the Tonga-Lau Back-arc Mantle
	Wei S.S.; Wiens D.A.
发表日期	2020
ISSN	21699313
卷号	125 期号:1
英文摘要	Seismic attenuation measures energy loss during seismic wave propagation and quantifies the relaxation of rocks' elastic moduli. Abundant seismic studies have observed shear attenuation, but few have quantified bulk attenuation (bulk modulus relaxation), and these studies controversially locate finite bulk attenuation in different parts of the Earth, from the asthenosphere to the inner core. Here we present conclusive evidence localizing bulk attenuation to a specific region of the uppermost mantle. By analyzing amplitude spectral decay of P and S waves from Tonga earthquakes recorded at local seismic stations, we observe unusually low QP/QS ratios (<1.5) in the Tonga-Lau mantle wedge. All seismic raypaths with significant path-average bulk attenuation (Qκ −1 > 0.01 or Qκ < 100) are confined to the region immediately beneath the Lau back-arc spreading centers west of the Tonga Arc. Tomography results show that the highest bulk attenuation (Qκ −1 = 0.037 ± 0.008 or Qκ = 27.0 ± 0.2) is about 75% of the in situ shear attenuation. The observed high bulk attenuation anomalies coincide with an inferred zone of partial melting, suggesting that the causative mechanism involves either infinitesimal movement of melt through pores or changes in melt fraction in response to seismic waves. ©2019. American Geophysical Union. All Rights Reserved.
英文关键词	bulk attenuation; Lau back-arc basin; mantle partial melting; QP/QS ratio; Tonga subduction zone
语种	英语
来源期刊	Journal of Geophysical Research: Solid Earth
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/188023
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
推荐引用方式 GB/T 7714	Wei S.S.,Wiens D.A.. High Bulk and Shear Attenuation Due to Partial Melt in the Tonga-Lau Back-arc Mantle[J],2020,125(1).
APA	Wei S.S.,&Wiens D.A..(2020).High Bulk and Shear Attenuation Due to Partial Melt in the Tonga-Lau Back-arc Mantle.Journal of Geophysical Research: Solid Earth,125(1).
MLA	Wei S.S.,et al."High Bulk and Shear Attenuation Due to Partial Melt in the Tonga-Lau Back-arc Mantle".Journal of Geophysical Research: Solid Earth 125.1(2020).