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Comparison of broadband and short‐period seismic waveform stacks: Implications for upper‐mantle discontinuity structure
Author(s) -
Ritsema Jeroen,
Hagerty Michael,
Lay Thorne
Publication year - 1995
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 - 10.1029/95gl03318
Subject(s) - geology , seismology , broadband , discontinuity (linguistics) , subduction , mantle (geology) , waveform , amplitude , period (music) , geophysics , tectonics , radar , optics , acoustics , mathematical analysis , telecommunications , physics , mathematics , computer science
Stacks of short‐period and broadband seismic waveforms from four deep (h > 550 km) earthquakes in South America recorded in California exhibit small amplitude signals between the direct P and surface‐reflected pP phases. The anomalous and variable slownesses of these signals in short‐period stacks, as well as differences between short‐period and broadband stacks suggest that the weak arrivals originate by reflection from laterally varying structure in the mantle near the subduction zone. The only structure consistently producing near‐source and near‐receiver reflections is the “410 km” discontinuity, which varies in depth by ±10 km, and has an impedance contrast comparable with that predicted by reference Earth models.