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Splitting function measurements for Earth's longest period normal modes using recent large earthquakes
Author(s) -
Deuss Arwen,
Ritsema Jeroen,
van Heijst Hendrik
Publication year - 2011
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 - 10.1029/2010gl046115
Subject(s) - gravimeter , seismology , physics , earth's rotation , geology , geodesy , event (particle physics) , function (biology) , geophysics , quantum mechanics , evolutionary biology , biology , casing
Recent megathrust earthquakes, such as the 23 June 2001 Peru event, the Sumatra events of 2004 and 2005 and the 27 February 2010 Chile event, have given us the opportunity to measure splitting of the longest period normal modes. We use wave spectra to make robust measurements for modes 0 S 2 , 0 S 3 , 0 S 4 , 2 S 1 and 1 S 2 . Singlet frequencies of these modes have been measured previously using gravimeters, but here we use seismic records to observe splitting functions for 0 S 2 and 2 S 1 for the first time. Cross‐coupling with nearby modes is included to account for ellipticity and rotation of the Earth and results in significantly improved splitting function measurements for 0 S 3 , 0 S 4 and 1 S 2 compared with previous studies. The new splitting function measurements can easily be implemented in future tomographic modelling of aspherical velocity and, particularly, density structure.