Depth‐dependent attenuation in the uppermost inner core from the Taiwan short period seismic array PKP data

Abstract

Inner core attenuation properties from two spots were examined in detail using PKIKP and PKP(BC) phases with a distance range of between 147° and 154° as recorded by both the short‐period regional seismic array in Taiwan and the broadband stations of the German Regional Seismic Network. The ray paths from the six South American events to Taiwan sampled the inner core region beneath the eastern part of the northern Pacific Ocean, while those from Fiji to Europe reflected the inner core boundary under the western part of the northern Pacific Ocean. Results of this study show the depth‐dependent attenuation of Qp beneath the eastern part of the northern Pacific Ocean from 241±21.8 (at depths <210 km) to 337±46.5 (at depths >270 km) with a weighted mean of 305±25.4 within the frequency band 0.5∼2.0Hz. The average Qp under the western part of the northern Pacific Ocean is 160±33.5 (0.5 ∼ 1.5Hz) which is consistent with that previously reported. It is found that Qp under the western part of the northern Pacific is clearly lower than that under the eastern part. This discrepancy might be related to regional variations in the uppermost inner core.