Abstract
Short-period PcP phases from earthquakes in the western Aleutians recorded at the Canadian Yellowknife array (YKA) sample the core-mantle boundary (CMB) beneath the Alaskan Kenai peninsula and the Cook inlet. The PcP -to-P amplitude ratios for these events show large variability with some amplitude ratios more than an order of magnitude larger than predicted by radial Earth models such as IASP91 or PREM. The amplitude ratios vary laterally with PcP core-mantle boundary reflection points showing a ∼1° region with exceptionally large amplitude ratios. It is likely that the variability in relative PcP amplitudes is due in large part to CMB topography. Other mechanisms, such as radiation pattern; mantle attenuation; focusing and defocusing; and core-mantle boundary velocity and density perturbations could cause variations on scale-lengths of less than a degree as found in this study, but are unable to produce variations as large as those we observe.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 19-36 |
| Number of pages | 18 |
| Journal | Physics of the Earth and Planetary Interiors |
| Volume | 145 |
| Issue number | 1-4 |
| DOIs | |
| State | Published - Jul 30 2004 |
| Externally published | Yes |
Bibliographical note
Funding Information:We thank the Geological Survey of Canada and the CNSN datacenter for the YKA data. We thank Klaus Stammler for his SeismicHandler software (Stammler, 1993) . We thank Rainer Kind for making his reflectivity code available to us. Constructive reviews by John Castle and Paul Earle helped to improve this manuscript. Figures are produced using the GMT software by Wessel and Smith (1995) . Funding for this study was provided by NSF grant EAR-9905733 and IGPP grant 02-GS-011. This is CSIDE contribution 477.
Keywords
- Alaska
- Core-mantle boundary
- PcP
- Reflection coefficient
- Seismic array