TY - JOUR
T1 - Interior structure of the Moon
T2 - Constraints from seismic tomography, gravity and topography
AU - Steinberger, Bernhard
AU - Zhao, Dapeng
AU - Werner, Stephanie C.
N1 - Funding Information:
Figures were made using GMT ( Wessel and Smith, 1998 ). B.S. and S.C.W. are supported by the Norwegian Research Council through a Centre of Excellence grant to The Centre for Earth Evolution and Dynamics and partially by the European Research Council under the European Union’s Seventh Framework Program (FP7/2007–2013)/ERC Grant agreement 267631 (Beyond Plate Tectonics). D.Z. is supported by a grant (Kiban-S 11050123) from Japan Society for the Promotion of Science (JSPS) and a grant (Shin-Gakujutsu 26106005) from MEXT. We thank three anonymous reviewers for constructive and detailed comments leading to considerable improvements of the manuscript.
Publisher Copyright:
© 2015 Elsevier B.V.
PY - 2015/8/1
Y1 - 2015/8/1
N2 - Seismic tomography can be combined with constraints from geoid, topography and other surface observations to gain information about mantle structure and dynamics. This approach has been taken with much success for the Earth mantle, and here it is, for the first time, applied to the Moon. Lunar tomography has much lower resolution as for the Earth and is mostly restricted to the near side, nevertheless we can assess under what assumptions the fit between predicted geoid (based on a tomography model) and observed geoid is best. Among the models tested, we find the most similar pattern (correlation about 0.5) if we only consider tomography below 225. km depth, if density anomalies cause little or no dynamic topography and if we compare to the geoid with the flattening (. l=. 2, m=. 0) term removed. This could mean that (a) like for the Earth, seismic anomalies shallower than 225. km are caused by a combination of thermal and compositional effects and therefore cannot be simply converted to density anomalies; (b) the lithosphere is sufficiently thick to prevent dynamic topography more than a small fraction of total topography; and (c) flattening is a "fossil" bulge unrelated to present-day mantle anomalies. However, we have to be cautious with interpreting our results, because for models with a comparatively higher correlation and a conversion from seismic velocity to density anomalies similar to the Earth's upper mantle, the amplitude of the predicted geoid is much lower than observed. This could either mean that the tomography model is strongly damped, or that the geoid is mostly due to shallow causes such as crustal thickness variations, with only a small part coming from the deeper mantle.
AB - Seismic tomography can be combined with constraints from geoid, topography and other surface observations to gain information about mantle structure and dynamics. This approach has been taken with much success for the Earth mantle, and here it is, for the first time, applied to the Moon. Lunar tomography has much lower resolution as for the Earth and is mostly restricted to the near side, nevertheless we can assess under what assumptions the fit between predicted geoid (based on a tomography model) and observed geoid is best. Among the models tested, we find the most similar pattern (correlation about 0.5) if we only consider tomography below 225. km depth, if density anomalies cause little or no dynamic topography and if we compare to the geoid with the flattening (. l=. 2, m=. 0) term removed. This could mean that (a) like for the Earth, seismic anomalies shallower than 225. km are caused by a combination of thermal and compositional effects and therefore cannot be simply converted to density anomalies; (b) the lithosphere is sufficiently thick to prevent dynamic topography more than a small fraction of total topography; and (c) flattening is a "fossil" bulge unrelated to present-day mantle anomalies. However, we have to be cautious with interpreting our results, because for models with a comparatively higher correlation and a conversion from seismic velocity to density anomalies similar to the Earth's upper mantle, the amplitude of the predicted geoid is much lower than observed. This could either mean that the tomography model is strongly damped, or that the geoid is mostly due to shallow causes such as crustal thickness variations, with only a small part coming from the deeper mantle.
KW - Gravity anomalies
KW - Moon interior structure
KW - Seismic tomography
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U2 - 10.1016/j.pepi.2015.05.005
DO - 10.1016/j.pepi.2015.05.005
M3 - Article
AN - SCOPUS:84930948552
VL - 245
SP - 26
EP - 39
JO - Physics of the Earth and Planetary Interiors
JF - Physics of the Earth and Planetary Interiors
SN - 0031-9201
ER -