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High‐resolution probing of inner core structure with seismic interferometry
Author(s) -
Huang HsinHua,
Lin FanChi,
Tsai Victor C.,
Koper Keith D.
Publication year - 2015
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2015gl066390
Subject(s) - inner core , interferometry , geology , seismology , core (optical fiber) , coda , geodesy , anomaly (physics) , seismic wave , seismic interferometry , geophysics , physics , optics , condensed matter physics
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 PKIKP 2 and PKIIKP 2 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.