Imperial College London
Portrait Picture

ProfessorMikeWarner

Faculty of Engineering, Department of Earth Science & Engineering

Professor
 
 
 
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Contact

 

+44 (0)20 7594 6535m.warner

 
 
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Assistant

 

Ms Daphne Salazar +44 (0)20 7594 7401

 
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Location

 

RSM 1.46CRoyal School of MinesSouth Kensington Campus

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Summary

 

Publications

Citation

BibTex format

@article{Christeson:2012:10.1029/2011JB008972,
author = {Christeson, GL and Morgan, JV and Warner, MR},
doi = {10.1029/2011JB008972},
journal = {Journal of Geophysical Research},
title = {Shallow oceanic crust: Full waveform tomographic images of the seismic layer 2A/2B boundary},
url = {http://dx.doi.org/10.1029/2011JB008972},
volume = {117},
year = {2012}
}
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RIS format (EndNote, RefMan)

TY  - JOUR
AB  - We present results of full-waveform tomographic inversions of four profiles acquired over young intermediate- and fast spreading rate oceanic crust. The mean velocity-depth functions from our study include a 0.25–0.30 km-thick low-velocity, low-gradient region beneath the seafloor overlying a 0.24–0.28-km-thick high-gradient region; together these regions compose seismic layer 2A. Mean layer 2A interval velocities are 3.0–3.2 km/s. The mean depth to the layer 2A/2B boundary is 0.49–0.54 km, and mean velocities within the upper 0.25 km of layer 2B are 4.7–4.9 km/s. Previous velocity analyses of the study areas using 1-D ray tracing underestimate the thickness of the high-gradient region at the base of layer 2A. We observe differences in the waveform inversion velocity models that correspond to imaging of the layer 2A event; regions with a layer 2A event have higher velocity gradients at the base of layer 2A. Intermittent high velocities, which we interpret as massive flows, are observed in the waveform inversion velocity models at 0.05–0.10 km below the seafloor (bsf) over 10–25% of the intermediate-spreading profiles and 20–45% of the fast spreading profiles. The high-gradient region located 0.25–0.54 km bsf at the base of layer 2A may be associated with an increased prevalence of massive flows, the first appearance of dikes (lava-dike transition zone), or with increased crack sealing by hydrothermal products. The upper portion of layer 2B, which begins at 0.49–0.54 km bsf, may correspond to sheeted dikes or the top of the transition zone of lavas and dikes.
AU  - Christeson,GL
AU  - Morgan,JV
AU  - Warner,MR
DO  - 10.1029/2011JB008972
PY  - 2012///
TI  - Shallow oceanic crust: Full waveform tomographic images of the seismic layer 2A/2B boundary
T2  - Journal of Geophysical Research
UR  - http://dx.doi.org/10.1029/2011JB008972
UR  - http://www.agu.org/pubs/crossref/2012/2011JB008972.shtml
VL  - 117
ER  -
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