Download Length scales of mantle heterogeneities from seismological

Length scales of mantle heterogeneities from
seismological perspective
Yingcai Zheng
w/ input from Ru-shan Wu and Thorne Lay
University of California, Santa Cruz
P(k)
???
Large scale
Small/medium scale Fine scale,
~1km
~100s-1000s
~10s km
k
km
Seismic velocity heterogeneities: Scale issue
Observational geometry: wavefront “distortion” of a teleseismic plane wave
logA(x)
ϕ(x)
Chernov,1950; Tatarskii 1971); Aki (1973) and others; Flatte and Wu
(1988); Zheng, Wu, Lay (2007), Zheng and Wu (2008). Incomplete …
Contour line spacing is every 20 deg in epicentral distance
Estimated slope is -2.56 for L-curve result in the shaded region
Estimated slope is -1.28 for L-curve result in the shaded region
Implications to CIDER inter-disciplinary
investigation
• Based on the seismic results: size and strength of the
multiscale heterogeneities, likely to be compositional.
• Assuming the origin of the heterogeneity,e.g., oceanic crust
•  long-term evolution of the Earth’s interior: vol. of the
subducted oceanic crust retained in the mantle;
• layering of the heterogeneity and multiscale spectra of the
heterogeneity (CONVECTION)
•  mixing model of the mantle (PETRO)
•  Compare with spectra of isotopic ratios along ocean ridges
with seismic heterogeneity spectra (GEOCHEM)