the D'' Discontinuity
of the D''
Fine-Scale Topography of the D'' Discontinuity
and its Correlation to Volumetric Velocity Fluctuations
We constrained the correlation of the topography
of the D'' discontinuity to volumetric velocity fluctuations.
We used data obtained from Hi-net tiltmeters
deployed by the National Research Institute for Earth Science
and Disaster Prevention, Japan, and conducted stacking
and migration to map the discontinuity beneath the southwestern
We compared the obtained map with the distribution of
ScS-S travel time residuals,
an index of volumetric velocity fluctuations
in the lowermost mantle.
We detected the fine-scale (of the order of a few hundred
kilometers) topography of the D'' discontinuity
as well as fine-scale volumetric velocity fluctuations.
Regions with relatively higher velocities generally have
a discontinuity with shallower depths, and
those with relatively lower velocities generally have a discontinuity
with deeper depths.
The scattering plot between the observed depths of the
the observed ScS-S residuals appears to exhibit a nonlinear trend.
These results may suggest the existence of both thermal
and chemical anomalies, such as those seen in thermochemical plumes.
- Takeuchi, N. & Obara, K.,
Fine-scale topography of the D'' discontinuity and its correlation to
volumetric velocity fluctuations,
Phys. Earth Planet. Int., 183, 126-135.