Velocity structure of upper-mantle transition zones beneath central Eurasia from seismic inversion using genetic algorithms

• Published in: Geophysical Journal International
• Main Authors: Neves, Fernando A., Singh, Satish C., Priestley, Keith F.
• Format: Text
• Language: English
• Published: Oxford University Press 1996
• Subjects: Articles; Yamal Peninsula; Siberia
• Online Access: http://gji.oxfordjournals.org/cgi/content/short/125/3/869; https://doi.org/10.1111/j.1365-246X.1996.tb06030.x

We present velocity constraints for the upper-mantle transition zones beneath Central Siberia based on observations of the 1982 RIFT Deep Seismic Sounding (DSS) profile. The data consist of seismic recordings of a nuclear explosion in north-western Siberia along a 2600 km long seismic profile extending from the Yamal Peninsula to Lake Baikal. We invert seismic data from the mantle transition zones using a non-linear inversion scheme using a genetic algorithm for optimization and the WKBJ method to compute the synthetic seismograms. A statistical error analysis using a graph-binning technique was performed to provide uncertainty values in the velocity models. Our best model for the upper-mantle velocity discontinuity near 410 km depth has a two-stage velocity-gradient structure, with velocities increasing from 8.70–9.25 km s−1 over a depth range of 400–415 km, a gradient of 0.0433 s−1, and from 9.25–9.60 km s−1 over a depth range of 415–435 km, a gradient of 0.0175 s−1. This derived model is consistent with other seismological observations and mineral-physics models. The model for the velocity discontinuity near 660 km depth is simple, sharp and includes velocities increasing from 10.15 km s−1 at 655 km depth to 10.70 km s−1 at 660 km depth, a gradient of 0.055 s−1.