Journal Article•
Fast evaluation of source parameters from isolated surface-wave signals. Part I. Universal tables
01 Aug 1970-Bulletin of the Seismological Society of America (Seismological Society of America)-Vol. 60, Iss: 4, pp 1337-1387
TL;DR: In this article, the spectral displacements of seismic surface waves from shear dislocations in flat multilayered earth models were prepared for spectral radiation patterns of amplitudes and initial phases.
Abstract: Tables for spectral displacements of seismic surface waves from shear dislocations in flat multilayered earth models were prepared. Earth response functions for seven modes (R_(11), R_(21), R_(12), L_0, L_1, L_2, L_3) at six periods (300 sec, 250 sec, 200 sec, 150 sec, 100 sec, 50 sec) and three paths (continental, oceanic, shield) were calculated for the source-depth range of 10 to 600 km at intervals of 5 km until 200 km, and thereafter at intervals of 10 km. Ground motion is given in micron-seconds for the three fundamental shear dislocations, each of strength U_0dS = 10^3 (m × km^2) and a delta-function time-dependence.
The tables provide the means for rapid evaluation of source parameters from spectral radiation patterns of amplitudes and initial phases.
Citations
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TL;DR: In this article, the mechanism of the Aleutian islands earthquake of 1946 and the Sanriku earthquake of 1896 is studied on the basis of the data on seismic waves from 5 to 100 s and on tsunamis.
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TL;DR: In this article, a method for rapid retrieval of earthquake-source parameters from long-period surface waves is developed, which can be used for warning of tsunamis in real time.
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TL;DR: In this article, a long-period strain seismogram recorded at Pasadena is used to determine the focal process of the 1960 Chilean earthquake, and a simple dislocation model is proposed to explain this precursory displacement.
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TL;DR: The Gibbs fracture zone (52°N, 35°W) is one of the major transform faults in the Atlantic as discussed by the authors, and the seismic moments determined by using the long-period (40-200 sec) G_1 and R_1 waves are 3.4 · 10^(26) and 4.5 · 10−26) dyne · cm, respectively.
302 citations
TL;DR: In this paper, seismic moments for 12 major earthquakes in central Asia from 1911 to 1967 were calculated from long-period Rayleigh and Love wave spectral densities, with fault lengths estimated from geological field observations of surface faulting, intensity distributions or master event relocations of aftershocks.
Abstract: Seismic moments for 12 major earthquakes (M ≥ 7.6) in central Asia from 1911 to 1967 were calculated from long-period Rayleigh and Love wave spectral densities. With fault lengths estimated from geological field observations of surface faulting, intensity distributions, or master event relocations of aftershocks, the calculated moments place bounds on the average slip and fault widths. The following table summarizes the calculated moments, estimated fault lengths, and inferred possible average displacements.
298 citations
References
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TL;DR: In this paper, a matrix formulation is used to derive integral expressions for the time transformed displacement fields produced by simple sources at any depth in a multilayered elastic isotropic solid half-space.
Abstract: A matrix formulation is used to derive integral expressions for the time transformed displacement fields produced by simple sources at any depth in a multilayered elastic isotropic solid half-space. The integrals are evaluated for their residue contribution to obtain surface wave displacements in the frequency domain. The solutions are then generalized to include the effect of a surface liquid layer. The theory includes the effect of layering and source depth for the following: (1) Rayleigh waves from an explosive source, (2) Rayleigh waves from a vertical point force, (3) Rayleigh and Love waves from a vertical strike slip fault model. The latter source also includes the effect of fault dimensions and rupture velocity. From these results we are able to show certain reciprocity relations for surface waves which had been previously proved for the total displacement field. The theory presented here lays the ground work for later papers in which theoretical seismograms are compared with observations in both the time and frequency domain.
441 citations
TL;DR: In this paper, a theory for the propagation of seismic surface-waves from finite moving sources is proposed, in which basic solutions for surface displacements from directional sources are integrated to obtain the effect of a moving fault with arbitrary dip angle.
Abstract: A theory is proposed for the propagation of seismic surface-waves from finite moving sources. The method consists of obtaining, in the first place, basic solutions for surface displacements from directional sources. These solutions are integrated to obtain the effect of a moving fault with arbitrary dip angle. Displacements are evaluated for Rayleigh and Love-waves, at long ranges. It is shown that the dimensions of the source and the speed of rupture play an important role in the wave-pattern and cannot be ignored whenever the dimensions of the source are of the order of the radiation's dominant-wave-length. It is demonstrated how this theory may lead to a derivation of the velocity of rupture and the fault-length from seismic records of a single station. Evidence is furnished both from two-dimensional model experiments and the Chilean Earthquake of May 1960.
382 citations
TL;DR: In this article, the authors generalized the treatment of Rayleigh waves from single and double couple point sources of arbitrary orientation in a semi-infinite homogeneous medium to the case of a medium composed of an arbitrary number of parallel homogeneous layers by the use of layer matrices.
Abstract: A previous treatment of the radiation pattern of Rayleigh waves from single and double couple point sources of arbitrary orientation in a semi-infinite homogeneous medium is generalized to the case of a medium composed of an arbitrary number of parallel homogeneous layers by the use of layer matrices. Source coefficients are given for a single force, a force dipole without torque, a single couple, and a double couple without torque, all for arbitrary orientation vectors, and also for a spherically symmetrical compressional source. For the simplest case permitting the existence of Love waves, a single finite layer over a semi-infinite medium, expressions for the Love wave radiation pattern are given explicitly in a form comparable to that previously given for Rayleigh waves in the homogeneous case.
202 citations
TL;DR: In this paper, an explicit expression for the far displacement field of Rayleigh and Love waves generated by force configurations which served to simulate shear-type faults with arbitrary dip and slip was obtained for a Gutenberg flat continental earth model with 23 layers.
Abstract: Explicit compact expressions were obtained for the far displacement field of Rayleigh and Love waves generated by force configurations which served to simulate shear-type faults with arbitrary dip and slip The medium transfer functions for dipolar sources were computed for a Gutenberg flat continental earth model with 23 layers These were then used to obtain universal radiation pattern charts for couple- and double-couple-type sources at various depths over the period range 50 to 350 sec It was demonstrated by means of few typical examples that the radiation patterns of Rayleigh waves may depend strongly on the depth of the source, and unlike the fundamental Love mode may be rather sensitive to small variations in frequency For a given source and frequency the radiation pattern may differ considerably from one mode to another
170 citations
TL;DR: In this article, the authors derived integral expressions for the displacement field due to a localized buried source of the m th order in a layered half space, and the results for a horizontal thrust are found to be the same as for a vertical dip-slip fault.
Abstract: Hansen9s expansion is used to derive integral expressions for the displacement field due to a localized buried source of the m th order in a layered half space. The dipolar case ( m ≦ 2) is worked out in detail for arbitrary source-depth in the layer and in the substratum. A new type of representation of the source is used which gives the final results in a concise form. Explicit expressions for the displacements at the free surface are obtained for a center of explosion, a vertical strike-slip fault and a vertical dip-slip fault. The results for a horizontal thrust are found to be the same as for a vertical dip-slip fault. The relations between the Galerkin vector and the biharmonic eigenvectors are clarified. It is shown that the Galerkin-Boussinesq solution for the elastic half space cannot be extended to structures of higher complexity, except for a few simple sources. On the other hand, the Hansen Solution is valid for a wide class of sources and structures. Both dynamic and static regimes are considered.
102 citations