A new catalogue of normal-mode splitting function measurements up to 10 mHz

Abstract

The splitting of the Earth's free-oscillation spectra places important constraints on the wave speed and density structure of the Earth's mantle and core. We present a new set of 164 self-coupled and 32 cross-coupled splitting functions. They are derived from modal spectra up to 10 mHz for 91 events with Mw ≥ 7.4 from the last 34 yr (1976–2010). Our data include the 2001 June 23 Peru event (Mw = 8.4), the Sumatra events of 2004 (Mw = 9.0) and 2005 (Mw = 8.6), the 2008 Wenchuan, China event (Mw = 7.9) and the 2010 Chile event (Mw = 8.8). The new events provide significant improvement of data coverage particularly in continental areas. Almost half of the splitting functions have never been measured before. In particular, we measured 33 new modes sensitive to mantle compressional wave velocity, 10 new inner-core sensitive modes and 22 new cross-coupled splitting functions. These provide new constraints on the large-scale compressional structure of the mantle and the odd-degree structure of the mantle and inner core and can be used in future inversions of heterogeneous Earth structure. Our new splitting function coefficient data set will be available online.