Premium
A low‐velocity lamella in D″
Author(s) -
Thomas Carsten,
Weber Michael,
Ag Amotz,
Hofstetter Abraham
Publication year - 1998
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/98gl52103
Subject(s) - amplitude , geology , lamella (surface anatomy) , mantle (geology) , core–mantle boundary , reflection (computer programming) , seismology , anomaly (physics) , phase velocity , phase (matter) , geophysics , travel time , physics , optics , paleontology , condensed matter physics , engineering , quantum mechanics , computer science , transport engineering , programming language
We investigate local variations of the P ‐wave velocity structure in the lower‐most mantle ( D″ ) beneath Western Siberia. Data of earthquakes in the Kurile Island region recorded at short‐period stations of the Israel Seismic Network show a high‐amplitude phase ( PdP ) after P which cannot be explained by standard Earth models. We present evidence that this phase is a reflection from a low‐velocity lamella in D″ . The best, locally valid, 1‐D model consists of a low‐velocity lamella 282km (±20km) above the core‐mantle boundary with a thickness of 8km (±3km). The very high amplitudes of PdP cannot be reproduced by a 1‐ D model. The PdP observation reported here is a regional feature. The area north of it does not show a P ‐velocity anomaly, whereas further north positive jumps in P ‐ and S ‐velocity have been documented. Our observation once more demonstrates the complexity of D″.