High-resolution probing of inner core structure with seismic interferometry
KAUST Grant NumberOCRF-2014-CRG3-2300
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Abstract© 2015. American Geophysical Union. All Rights Reserved. Increasing complexity of Earth's inner core has been revealed in recent decades as the global distribution of seismic stations has improved. The uneven distribution of earthquakes, however, still causes a biased geographical sampling of the inner core. Recent developments in seismic interferometry, which allow for the retrieval of core-sensitive body waves propagating between two receivers, can significantly improve ray path coverage of the inner core. In this study, we apply such earthquake coda interferometry to 1846 USArray stations deployed across the U.S. from 2004 through 2013. Clear inner core phases PKIKP2 and PKIIKP2 are observed across the entire array. Spatial analysis of the differential travel time residuals between the two phases reveals significant short-wavelength variation and implies the existence of strong structural variability in the deep Earth. A linear N-S trending anomaly across the middle of the U.S. may reflect an asymmetric quasi-hemispherical structure deep within the inner core with boundaries of 99°W and 88°E.
CitationHuang H-H, Lin F-C, Tsai VC, Koper KD (2015) High-resolution probing of inner core structure with seismic interferometry. Geophysical Research Letters 42: 10,622–10,630. Available: http://dx.doi.org/10.1002/2015GL066390.
SponsorsWe thank Alex Song for helpful discussion. We also thank H. Tkalcic and an anonymous reviewer for constructive comments. All waveform data used in this study can be downloaded from the IRIS Data Management Center. This work was supported by National Science Foundation grants, EAR-1316348 and CyberSEES-1442665, the King Abdullah University of Science and Technology (KAUST) under Award No. OCRF-2014-CRG3-2300, and the grant of Ministry of Science and Technology, Taiwan, 104-2917-I-564 -052.
JournalGeophysical Research Letters