Waveform inversion of mantle Love waves:the Born seismogram approach

Normal mode theory, extended to the slightly laterally heterogeneous Earth by the first-order Born approximation, is applied to the waveform.inversion of mantle Love waves (200-500 sec) for the Earth's lateral heterogeneity at 1=2 and ' a spherically symmetric anelasticity (Q µ) structure.The data are from the Global Digital Seismograph Network (GDSN).The 1=2 pattern is very similar to the results of other studies that u-sed either different methods, such as phase velocity measurements and multiplet location measurements, or a different data set, such as ma^itle Rayleigh waves from different instruments.The results are carefully analyzed for variance reduction and are most naturally explained by heterogeneity in the upper 420 km.Because of the poor resolution of the data set for the deep interior, however, a fairly large heterogeneity in the transition zones, of the order of up to 3.5% in shear wave velocity, is allowed.It is noteworthy that Love waves of this period range cannot constrain the structure a U 6OF, POOR QUALITY