. The Earth beneath the sea : History . DATA OF 24 SEPT 1958 GULF OF ALASKA TO HONOLULU + Transverse component o Vertical component o > Q. O Dormon 8055 a(km/sec) /3 (km/sec) p[ 9/ml) h(km) - 20 25 Period (sec) 30 Fig. 13. Typical oceanic dispersion data, derived from the seismograms of Fig. 11, are plotted with theoretical surface-wave group-velocity dispersion data. The theoretical curves were computed on the basis of the layered structure indicated. Agreement between theoretical and experimental data is good in the Rayleigh mode owing to proper choice
. The Earth beneath the sea : History . DATA OF 24 SEPT 1958 GULF OF ALASKA TO HONOLULU + Transverse component o Vertical component o > Q. O Dormon 8055 a(km/sec) /3 (km/sec) p[ 9/ml) h(km) - 20 25 Period (sec) 30 Fig. 13. Typical oceanic dispersion data, derived from the seismograms of Fig. 11, are plotted with theoretical surface-wave group-velocity dispersion data. The theoretical curves were computed on the basis of the layered structure indicated. Agreement between theoretical and experimental data is good in the Rayleigh mode owing to proper choice of the thickness of water plus mud (layers one and two), which deter- mines the period of the steep portion of the curve. However, poor agreement in the first Love and first shear modes is due mainly to an incorrect choice of parameters to represent the mud. Factors related to the presence or absence of various surface-wave types on seismograms were discussed by Oliver, Ewing and Press (1955) who compiled the geographical data of Fig. 14. Primarily, on seismograms written at Hawaii short-period waves predominate for shocks in the area including the Easter Island Rise, the west coast of North America and the Aleutians. For shocks elsewhere on the Pacific margins, long-period waves predominate at Hawaii. When two stations are on the same azimuth from a shock, the appearance of long-period waves is favored at the more distant station while short-period
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Keywords: ., bookcentury1900, bookcollectionbiodivers, booksubjectoceanbottom
