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Seismic velocities of upper oceanic crust
Author(s) -
Chapman N. R.,
Hannay D. E.
Publication year - 1994
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 - 10.1029/94gl01690
Subject(s) - geology , crust , seismology , reflection coefficient , oceanic crust , inversion (geology) , hydrothermal circulation , upper crust , geodesy , reflection (computer programming) , shear (geology) , geophysics , petrology , tectonics , optics , subduction , physics , computer science , programming language
New measurements are reported for the seismic velocities in upper oceanic crust (layer 2A) at off‐axis sites along a track at 34° N in the Pacific where the sediments were thin (< 33m) and the crustal age increased from 42 to 63 m.y. The data were obtained in experiments designed to measure the reflection coefficient at each site using a horizontal line array. The reflection coefficient versus angle information was inverted for the seismic velocities using a nonlinear inversion technique based on a simulated annealing search algorithm. The p wave velocity increased from 2.7 to 3.1 km/s along the track, and the shear velocity in‐creased from about 1.0 to 1.6 km/s. These results suggest that the aging process controlled by passive hydrothermal circulation is continuing at these sites.