Velocity structure of upper-mantle transition zones beneath central eurasia from seismic inversion using genetic algorithms |
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| Authors: | Fernando A Neves Satish C Singh Keith F Priestley |
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| Institution: | BIRPS, Bullard Laboratories, Madingley Rise, Madingley Road, Cambridge, CB3 0EZ, UK;Bullard Laboratories, Madingley Rise, Madingley Road, Cambridge, CB3 0EZ, UK |
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| Abstract: | 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. |
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| Keywords: | inversion seismic velocities transition upper mantle |
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