Sandvol, E., Seber, D., Calvert, A., and Barazangi, M.
Grid search modeling of receiver functions: Implications for crustal structure
in the Middle East and North Africa
Journal of Geophysical Research, 103, 26899-26917, 1998.
A grid search is used to estimate average crustal
thickness and shear wave velocity structure beneath 12 three-component broadband
seismic stations in the Middle East, North Africa, and nearby regions. The crustal
thickness in these regions is found to vary from a minimum of 8.0 +/- 1.5 km in
East Africa (Afar) region to possibly a maximum of 64 +/- 4.8 km in the lesser
Caucasus. Stations located within the stable African platform indicate a crustal
thickness of about 40 km. Teleseismic three-component waveform data produced by
165 earthquakes are used to create receiver function stacks for each station.
Using a grid search, we have solved for the optimal and most simple shear velocity
models beneath all 12 stations. Unlike other techniques (linearized least squares
or forward modeling), the grid search methodology guarantees that we solve for
the global minimum within our defined model parameter space. Using the grid search,
we also qualitatively estimate the least number of layers required to model the
observed receiver functions' major seismic phases (e.g., PSMoho). A jackknife
error estimation method is used to test the stability of our receiver function
inversions for all 12 stations in the region that had recorded a sufficient number
of high-quality broadband teleseismic waveforms. Five of the 12 estimates of crustal
thickness are consistent with what is known of crustal structure from prior geophysical
work. Furthermore, the remaining seven estimates of crustal structure are in regions
for which previously there were few or no data about crustal thickness.
An edited version of this paper was published
by AGU. Copyright 1998 American Geophysical Union.
Link to AGU
Key Figures and Captions
A map showing the grid search results of crustal thickness and prior, if available,
estimates of crustal thickness (shown in parentheses), and jackknife error estimates
in the Middle East and Africa.