Scattered P'P' waves observed at short distances
Bulletin of the Seismological Society of America
By: Paul S. Earle, Sebastian Rost, Peter M. Shearer, and Christine Thomas
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Abstract
We detect previously unreported 1 Hz scattered waves at epicentral distances between 30° and 50° and at times between 2300 and 2450 s after the earthquake origin. These waves likely result from off-azimuth scattering of PKPbc to PKPbc in the upper mantle and crust and provide a new tool for mapping variations in fine-scale (10 km) mantle heterogeneity. Array beams from the Large Aperture Seismic Array (LASA) clearly image the scattered energy gradually emerging from the noise and reaching its peak amplitude about 80 s later, and returning to the noise level after 150 s. Stacks of transverse versus radial slowness (ρt, ρr) show two peaks at about (2, -2) and (-2,-2) s/°, indicating the waves arrive along the major arc path (180° to 360°) and significantly off azimuth. We propose a mantle and surface PKPbc to PKPbc scattering mechanism for these observations because (1) it agrees with the initiation time and distinctive slowness signature of the scattered waves and (2) it follows a scattering path analogous to previously observed deep-mantle PK•KP scattering (Chang and Cleary, 1981). The observed upper-mantle scattered waves and PK•KP waves fit into a broader set of scattered waves that we call P′•d•P′, which can scatter from any depth, d, in the mantle.
Suggested Citation
Earle, P.S., Rost, S., Shearer, P., Thomas, C., 2011, Scattered P'P' waves observed at short distances: Bulletin of the Seismological Society of America, v. 101, no. 6, p. 2843-2854, https://doi.org/10.1785/0120110157.
ISSN: 1943-3573 (online)
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Scattered P'P' waves observed at short distances |
| Series title | Bulletin of the Seismological Society of America |
| DOI | 10.1785/0120110157 |
| Volume | 101 |
| Issue | 6 |
| Publication Date | December 08, 2011 |
| Year Published | 2011 |
| Language | English |
| Publisher | Seismological Society of America |
| Contributing office(s) | Rocky Mountain Mapping Center |
| Larger Work Type | Article |
| Larger Work Subtype | Journal Article |
| Larger Work Title | Bulletin of the Seismological Society of America |
| First page | 2843 |
| Last page | 2854 |