No abstract

No abstract

No abstract

No abstract

S U M M A R YQ P factor at the top of the inner core (IC) is derived using the amplitude spectral ratio (PKPbc versus PKPdf) method applied to the waveforms of suitable, strong (magnitude >6.0) intermediate depth and deep (h > 150 km) earthquakes recorded at some selected South American stations. In most cases, the sampled volume of the IC is centred beneath the Pacific Ocean, but some Q P values correspond to volumes under South Africa and under Northern Atlantic. The obtained value of Q P is 323 ± 16 (at 95 per cent confidence level), close to a normal (Gaussian) distribution. The maximum depth of penetration of the PKPdf phase into the IC is roughly 333 km, suggesting a possible increase of Q P with depth, although the large scatter in data prevents a definite conclusion. As regards the geographical patterns no variation was observed.