Mathematics – Logic
Scientific paper
Dec 2001
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2001agufm.s12a0574n&link_type=abstract
American Geophysical Union, Fall Meeting 2001, abstract #S12A-0574
Mathematics
Logic
7203 Body Wave Propagation, 7218 Lithosphere And Upper Mantle, 7219 Nuclear Explosion Seismology
Scientific paper
Strong scattered arrivals at 800-1400 km offset and clear travel time delays at ~900-1000 km offset are consistently observed in the four Peaceful Nuclear Explosion (PNE) seismic sections of the 3500 km long E-W trending profile Kraton. In combination, these features give evidence of an ~85 km thick inhomogeneous low-velocity layer in the Siberian upper mantle. The top of the anomalous zone is situated at ~100 km depth (the 8 degree discontinuity). Similar characteristics of the seismic wavefield are observed in the data sections of the ~3000 km long PNE profile Meteorite which crosses the central part of profile Kraton in a N-S direction. We model the inhomogeneous zone below the 8 degree discontinuity by continuous, random velocity fluctuations which are described by a van Karmann distribution function with a Hurst number of 0.5. The full waveform seismic response of a suite of stochastic velocity models is calculated using two-dimensional elastic and visco-elastic finite-difference techniques. The calculated seismic sections resemble the PNE data for models where the fluctuations have a horizontal correlation length of 5-10 km, a vertical correlation length not greater than 5 km and a standard deviation of about 2% of the average background velocity. Our study shows that inhomogeneities likely to be situated at lower crustal levels and velocity fluctuations proposed to exist in the uppermost mantle from the Moho to about 100 km depth give rise to scattered phases that do not match the observed key features. Therefore, the observations that we are concerned with may not be simply explained by shallow structures. The preferred seismic velocity model is in agreement with an upper mantle model in which the low-velocity zone below the 8 degree discontinuity may contain small amounts of partially molten or almost molten material. The combined effects of rheological weakening and small-scale anisotropy may also account for the low-velocity scattering layer.
Nielsen Lance
Solodilov Leonid
Thybo Hans
No associations
LandOfFree
Seismic Scattering in a Low-Velocity Layer From 100-200 km Depth in the Siberian Mantle does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Seismic Scattering in a Low-Velocity Layer From 100-200 km Depth in the Siberian Mantle, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Seismic Scattering in a Low-Velocity Layer From 100-200 km Depth in the Siberian Mantle will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1239892