Astronomy and Astrophysics – Astronomy
Scientific paper
May 2002
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2002geoji.149..463p&link_type=abstract
Geophysical Journal International, Volume 149, Issue 2, pp. 464-482.
Astronomy and Astrophysics
Astronomy
23
: Crust, Europe, Middle East, North Africa, Surface Waves, Upper Mantle
Scientific paper
We estimate the crust and upper-mantle seismic velocity structure in North Africa, southern Europe, and the Middle East using our surface-wave dispersion tomography results from a previous study. The surface wave tomography study provided high-resolution coverage across the region from more than 6800 Rayleigh and 3800 Love wave paths over the period range from 10-60 s. We have also included additional tomography results from 65 to 120 s. The tomography model provides average Rayleigh and Love wave dispersion curves for each 2°× 2° block in the region. We use these results to determine velocity structure by fitting the synthetic curves from simplified crust and upper-mantle models to the tomographic data for each block via a grid search. The grid search technique was chosen in order to map out the complete error space and to easily incorporate other data sets or a priori information. The initial grid search is conducted over sediment thickness, crustal velocity, crustal thickness, and upper-mantle velocity. To keep the grid search computationally reasonable, other parameters are held fixed (sediment velocity, Poisson's ratios, and density). Despite the well-known trade-off between crustal thickness and crustal velocity that occurs when fitting surface wave data, the initial grid search is quite successful in retrieving first order features, such as ocean-continent crustal thickness differences and crustal thickening in all but the oldest orogenic zones. We can resolve major sedimentary basins, active ridges, and see differences based on crustal age (e.g. Archean cratons vs Phanarozoic crust). To better control the trade-off inherent in fitting group velocity curves, we also explore using other information to better constrain the grid searches. In particular, we use a global sediment depth and velocity model to fix those parameters and a regional P n tomography to constrain the upper-mantle velocities. In this constrained grid search, we vary crustal thickness, upper and lower crustal velocities, and upper-mantle Poisson's ratio. This produces a somewhat better fit to the dispersion curves while simultaneously satisfying several datasets. While there are many similarities in the unconstrained and constrained model results, overall we believe the constrained grid search model is a better representation of reality. Finally, we compare and contrast our preferred velocity model with a number of other published models for this region. Within the resolution of the various models, they appear to be similar.
Pasyanos Michael E.
Walter William R.
No associations
LandOfFree
Crust and upper-mantle structure of North Africa, Europe and the Middle East from inversion of surface waves 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 Crust and upper-mantle structure of North Africa, Europe and the Middle East from inversion of surface waves, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Crust and upper-mantle structure of North Africa, Europe and the Middle East from inversion of surface waves will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1515780