abstract

The area of the Bering Sea and Alaska was studied in terms of shear velocity, density, and compressional velocity structure by applying a generalized inversion method to surface wave dispersion relationships in the period range from 10 to 100 sec.

Group velocity dispersion relationships in the area were obtained by applying the phase-matched filtering technique (Herrin and Goforth, 1977) to digitally recorded surface wave data. Corrections for instrument response and the sphericity of the Earth were applied to the dispersion observations. A new exact analytical method for the computation of Rayleigh wave phase velocity partial derivatives with respect to Earth parameters was formulated. With the phase velocity partial derivatives determined, the group velocity partial derivatives were computed by use of the fast and accurate method of Rodi et al. (1975), and were successfully incorporated into a generalized inversion method.

The study area was found to consist of three physiographic provinces, and the structure of the three regions was estimated as follows: in continental Alaska, the crustal thickness is about 43 km, and a low velocity zone extends from a depth of about 113 km to about 213 km. In the Bering Shelf region, the depth to the Mohorovičić discontinuity is about 28 km, and a low velocity zone ranges in depth from about 108 km to about 213 km. In the Aleutian Basin, the thickness of the crust is about 18 km, and a low velocity zone extends from a depth of about 60 km to about 220 km.

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