气候变化领域集成服务门户(CCPortal): Azimuthal Variation of Lithospheric Heterogeneity in the Northwest Pacific Inferred From Po/So Propagation Characteristics and Anomalously Large Ground Motion of Deep In-Slab Earthquakes

CCPortal

DOI	10.1029/2021JB021717
	Azimuthal Variation of Lithospheric Heterogeneity in the Northwest Pacific Inferred From Po/So Propagation Characteristics and Anomalously Large Ground Motion of Deep In-Slab Earthquakes
	Furumura T.; Kennett B.L.N.
发表日期	2021
ISSN	21699313
卷号	126 期号:5
英文摘要	High-frequency oceanic Pn/Sn (Po/So) phases (>2 Hz) recorded at ocean bottom seismometers in the northwest Pacific display strong azimuthal variations in propagation characteristics. In the direction parallel to former Pacific plate motion (N30°W), seismograms show a gentle rise at the onset of Po/So followed by large, long spindle-shaped coda; Po has a low-frequency (<0.25 Hz) precursor and much delayed high-frequency signals, showing weak dispersion with frequency. For orthogonal propagation, the onset of Po/So rises sharply and bursts of Po reverberations in the seawater follow. These differences indicate a strong azimuthal dependence of the scattering waveguide effect of the oceanic lithosphere. Numerical simulations of seismic waves in three-dimensional heterogeneous structures reveal that much of the observed Po/So propagation variability can be explained by laterally elongated fine-scale heterogeneity in the oceanic lithosphere, with a correlation distance of 20 km in the direction parallel to the magnetic anomaly, and a much shorter correlation distance in the perpendicular and depth directions. The longer axis corresponds to the observed Pn/Sn-wavespeed anisotropy in the northwest Pacific, so the heterogeneity pattern was also developed during the formation and growth of the Pacific plate; competing processes produce different styles of fine-scale effects. The elongated heterogeneity distributions in the oceanic lithosphere are carried into the subducting Pacific slab allowing energy from deep-focus earthquakes to propagate to large distances, producing observations of anomalously large ground motions in specific directions. The behavior can be matched with three-dimensional simulation of high-frequency wave propagation with a heterogeneous Pacific slab. © 2021. American Geophysical Union. All Rights Reserved.
英文关键词	fine-scale heterogeneity; numerical simulation; oceanic lithosphere; Pacific slab; Po/So phase
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/187149
作者单位	Earthquake Research Institute, The University of Tokyo, Bunkyo, Japan; Research School of Earth Sciences, The Australian National University, Canberra, ACT, Australia
推荐引用方式 GB/T 7714	Furumura T.,Kennett B.L.N.. Azimuthal Variation of Lithospheric Heterogeneity in the Northwest Pacific Inferred From Po/So Propagation Characteristics and Anomalously Large Ground Motion of Deep In-Slab Earthquakes[J],2021,126(5).
APA	Furumura T.,&Kennett B.L.N..(2021).Azimuthal Variation of Lithospheric Heterogeneity in the Northwest Pacific Inferred From Po/So Propagation Characteristics and Anomalously Large Ground Motion of Deep In-Slab Earthquakes.Journal of Geophysical Research: Solid Earth,126(5).
MLA	Furumura T.,et al."Azimuthal Variation of Lithospheric Heterogeneity in the Northwest Pacific Inferred From Po/So Propagation Characteristics and Anomalously Large Ground Motion of Deep In-Slab Earthquakes".Journal of Geophysical Research: Solid Earth 126.5(2021).