Tripartite phase velocity observations in laterally heterogeneous regions

Knopoff, L.; Berry, Michael; Schwab, Fred

doi:10.1029/jz072i010p02595

Cited by 29 publications

(14 citation statements)

References 2 publications

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“…Earlier works have already been done to compute phase velocities and the approach azimuth of the wave train for a given period, by means of a triangular network [Evernden, 1954]. Although the tripartite phase velocity method was designed to handle surface waves incident upon the array from any azimuth, the results of Knopoff et al[1967] showed that when the direction of propagation does not lie along one of the legs of the network, the phase velocities computed may be in significant error. Schwab and Kausel [ 1976] proposed the extension to quadripartite networks to solve this limitation.…”

Section: Paper Number 93gl00774mentioning

confidence: 99%

A test of the Great Circle Approximation in the analysis of surface waves

Alsina

Snieder

Maupin

1993

Geophysical Research Letters

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A new way of reconstructing wave fronts is developed for testing the validity of the great circle approximation in dispersion analysis of surface waves. Phase and time delays between pairs of stations of an array are used to reconstruct the wave fronts or surfaces of equal phase. This technique is applied to fundamental mode Rayleigh waves recorded at the NARS stations during the ILIHA (Iberian Lithosphere Heterogeneity and Anisotropy) project. The resulting wave fronts are compared with the theoretical ones, i.e. calculated assuming that the waves have traveled along the great circle path with a constant phase velocity, and the angle between both fronts is calculated. Waves traveling mostly through a laterally homogeneous oceanic path before arriving to the Iberian Peninsula are analyzed for the frequency range of 10 to 60 mHz. These show angles up to 8 degrees between the theoretical wave fronts and the wave fronts reconstructed using the delay data. This implies that we make a relative error less than 1% when calculating path‐averaged phase velocities ignoring the deviation of the arrival of the wave from the great circle direction.

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Section: Paper Number 93gl00774mentioning

confidence: 99%

A test of the Great Circle Approximation in the analysis of surface waves

Alsina

Snieder

Maupin

1993

Geophysical Research Letters

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“…Stars and triangles show the location of earthquakes (NEIC 2003;ISC 2003) and of the seismic stations whose records are used for group-velocity measurements, respectively. Several stations and events are located outside of the shown region, but the location of all events and stations used for group-velocity measurements in the study area are listed in Tables 1 and 2, respectively The penetration depth of our dataset is increased considering, in addition, published phasevelocity measurements (Knopoff and Panza 1977;Panza 1981) for Rayleigh waves that span over the period range from about 15-20 to about 150 s. The phase-velocity measurements in the following studies are collected: Payo (1965Payo ( , 1969, Berry and Knopoff (1967), Knopoff et al (1967), Sprecher (1976), Marillier (1981), Marillier and Mueller (1985), Badal et al (1996), and Lana et al (1997).…”

Section: Methods and Datamentioning

confidence: 99%

The shear-wave velocity structure of the lithosphere–asthenosphere system in the Iberian area and surroundings

Raykova

Panza

2010

Rend. Fis. Acc. Lincei

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The S-wave velocity model, to the depth of 300 km for the Iberian area and surroundings, is obtained with the non-linear inversion of Rayleigh wave tomographic data in the period range from 5 to 150 s. The three-dimensional model of the region is assembled from 74 juxtaposed one-dimensional cellular structures, sized 1°9 1°, by means of a local smoothing optimisation. The S-wave velocity model shows the almost constant velocity (*4.40 km/s) in the upper mantle beneath the Iberian Massif, the welldeveloped low-velocity zones in the Valencia Trough and under northwest Africa, and specific features of the upper mantle layering in the zone of the Iberian range. The thickness of the crust varies between 25 and 35 km with exceptions in the zones of the Valencia Trough (11-18 km) and Pyrenees (35-45 km). Our Vs models are well correlated with the geological structure along Transmed I and evidence several features of the lithosphere-asthenosphere system in the Betic-Rif domain: quite distinct Iberian, Alboran and Meseta crustal domains; relatively thin, well-developed lithosphere under the Rif system; and clearly defined boundary between the upper and lower asthenosphere. The cellular velocity model of the Betics, where ultrapotassic lamproitic magmatism is observed, has features similar to those of other three areas in the western Mediterranean where ultrapotassic lamproitic magmatism of different age is observed. The crust and upper mantle models in these four areas can be correlated with the age of the magmatism and the local heat flow, and outline how, starting from a naturally quite undifferentiated mantle where magma genesis is currently in progress, the differentiation in lithosphere and asthenosphere can take place in time.

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“…Some of the earliest such measurements of phase velocity, for periods <1 s, can be found in the oil exploration literature (e.g., Dobrin et al, 1951). Knopoff et al (1967) later found the two-station method to be superior to the tripartite method to minimize errors in phase shifts in the presence of lateral heterogeneity. Press (1956Press ( , 1957 used the triangulation or tripartite method to determine crustal structure in California from average phase velocities.…”

Section: Phase Velocitymentioning

confidence: 99%