[ { "id": "authors:wh10a-3r878", "collection": "authors", "collection_id": "wh10a-3r878", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150928-104929454", "type": "article", "title": "Fast evaluation of source parameters from isolated surface-wave signals. Part I. Universal tables", "author": [ { "family_name": "Ben-Menahem", "given_name": "Ari", "clpid": "Ben-Menahem-A" }, { "family_name": "Rosenman", "given_name": "Martin", "clpid": "Rosenman-M" }, { "family_name": "Harkrider", "given_name": "David G.", "clpid": "Harkrider-D-G" } ], "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 \u00d7 km^2) and a delta-function time-dependence.\nThe tables provide the means for rapid evaluation of source parameters from spectral radiation patterns of amplitudes and initial phases.", "issn": "0037-1106", "publisher": "Seismological Society of America", "publication": "Bulletin of the Seismological Society of America", "publication_date": "1970-08", "series_number": "4", "volume": "60", "issue": "4", "pages": "1337-1387" }, { "id": "authors:s9ayz-8p631", "collection": "authors", "collection_id": "s9ayz-8p631", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140811-131055746", "type": "article", "title": "Large scale processing of seismic data in search of regional and global stress patterns", "author": [ { "family_name": "Ben-Menahem", "given_name": "A.", "clpid": "Ben-Menahem-A" }, { "family_name": "Jarosch", "given_name": "H.", "clpid": "Jarosch-H" }, { "family_name": "Rosenman", "given_name": "M.", "clpid": "Rosenman-M" } ], "abstract": "A composite compute program has been devised for a fast reduction of multistation seismic data in the period range 50\u2013500 sec for mantle surface waves and 20\u2013100 sec for body waves.\n\nThe analysis aims at the reconstruction of the seismic source from the spectrum of its far radiation field and the correlation of its parameters with its depth, size and regional environment.\n\nThe capability of the computational procedure has been demonstrated in two studies of WWNSS records: one includes a spectral analysis of surface waves from a shallow shock in the Kurile Islands; the other includes a spectral analysis of P waves from 9 shocks in the depth range 550\u2013700 km at Fiji, Mariana, Java, Japan, Peru and Brazil.\n\nOther applications of the proposed data processing routine are foreseen; a tsunami warning system and focal depth determination from spectral modal ratios.\n\nIt is believed that a persistent search for stress patterns, based on the processing of a sufficiently large sample of seismic events, is essential to any future program of earthquake prediction.", "issn": "0037-1106", "publisher": "Seismological Society of America", "publication": "Bulletin of the Seismological Society of America", "publication_date": "1968-12", "series_number": "6", "volume": "58", "issue": "6", "pages": "1899-1932" }, { "id": "authors:73c5v-jhc89", "collection": "authors", "collection_id": "73c5v-jhc89", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140801-110558344", "type": "article", "title": "A procedure for source studies from spectrums of long-period seismic body waves", "author": [ { "family_name": "Ben-Menahem", "given_name": "Ari", "clpid": "Ben-Menahem-A" }, { "family_name": "Smith", "given_name": "Stewart W.", "clpid": "Smith-S-W" }, { "family_name": "Teng", "given_name": "Ta-Liang", "clpid": "Teng-T-L" } ], "abstract": "The well-known first motion method of Nakano and Byerly is extended, generalized and combined with recent new ideas in body wave theory in order to set up a routine procedure for extracting source parameters from spectral analysis of isolated P and S pulses recorded at a net of standardized stations around a non-shallow source.\n\nThe method consists of compensating the observed spectrums for instrumental and propagational effects. A combined study of the resulting radiation patterns, initial phases, and the initial amplitudes will render information regarding the spatial and temporal nature of deep and intermediate earthquake sources as seen through the spectral window of 10-100 seconds. The shorter periods can be used for source studies only if an accurate station correction is available.", "doi": "10.1785/BSSA0550020203", "issn": "0037-1106", "publisher": "Seismological Society of America", "publication": "Bulletin of the Seismological Society of America", "publication_date": "1965-04", "series_number": "2", "volume": "55", "issue": "2", "pages": "203-235" }, { "id": "authors:vsfnt-bxa78", "collection": "authors", "collection_id": "vsfnt-bxa78", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140507-122126998", "type": "article", "title": "Attenuation of Seismic Energy in the Upper Mantle", "author": [ { "family_name": "Anderson", "given_name": "Don L.", "clpid": "Anderson-D-L" }, { "family_name": "Ben-Menahem", "given_name": "Ari", "clpid": "Ben-Menahem-A" }, { "family_name": "Archambeau", "given_name": "C. B.", "clpid": "Archambeau-C-B" } ], "abstract": "The amplitude attenuation and phase dispersion for Love and Rayleigh waves in the period range 50 to 300 sec is determined from two earthquakes by digital techniques.\nA distribution of Q, or anelasticity, is determined for the upper mantle which satisfies the amplitude decay data for Love and Rayleigh waves and which is consistent with available body wave data. An argument is made for a longitudinal wave Q of about 2.4 to 2.6 times the\nQ for shear waves. This implies that very small losses are involved in pure compression compared to the losses in shear. This is an argument against the importance of certain mechanisms, such as thermoelastic losses, in the mantle. The Q for shear waves in the upper 400 km of the\nmantle seems to vary from about 50 to about 150. The Q for mantle Rayleigh waves is greater than the Q for mantle Love waves, both theoretically and experimentally. However,\nit is predicted that Q_R becomes less than Q_L at some period shorter than 50 sec, the crossover period being diagnostic of the thickness of the 'Q crust' or lithosphere.", "doi": "10.1029/JZ070i006p01441", "issn": "0148-0227", "publisher": "American Geophysical Union", "publication": "Journal of Geophysical Research", "publication_date": "1965-03-15", "series_number": "6", "volume": "70", "issue": "6", "pages": "1441-1448" }, { "id": "authors:6jsew-h6w02", "collection": "authors", "collection_id": "6jsew-h6w02", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20150928-113442846", "type": "article", "title": "Determination of source parameters by amplitude equalization of seismic surface waves: 2. Release of tectonic strain by underground nuclear explosions and mechanisms of earthquakes", "author": [ { "family_name": "Toks\u00f6z", "given_name": "M. Nafi", "clpid": "Toks\u00f6z-M-N" }, { "family_name": "Harkrider", "given_name": "David G.", "clpid": "Harkrider-D-G" }, { "family_name": "Ben-Menahem", "given_name": "Ari", "clpid": "Ben-Menahem-A" } ], "abstract": "The radiation patterns of Love and Rayleigh waves from three nuclear explosions (Hardhat, Haymaker, and Shoal) are studied to determine the nature of the asymmetry of radiation and the mechanism of Love wave generation. From a comparative study of different explosions it is reasoned that the Love waves are generated at the source of the explosion. The source function, represented as the superimposition of an isotropic dilatational component due to the explosion and a multipolar component due to the release of tectonic strain energy, is consistent with the observed radiation patterns and the amplitude spectrums. The amount of seismic energy due to the strain release is computed. In some cases (Haymaker and Shoal) it is found that this energy may be due to the relaxation of the pre-stressed medium by the explosion-formed cavity. In the case of Hardhat it is concluded that the explosion must have triggered some other strain release mechanism, such as an earthquake. The amplitude equalization method is applied to surface waves from an earthquake to determine the source parameters. From only the amplitude spectrums and radiation patterns of Love and Rayleigh waves, the source functions, source depth, strike and dip of the fault plane, and the rake of displacement are determined for the July 20, 1964, Fallon earthquake.", "doi": "10.1029/JZ070i004p00907", "issn": "0148-0227", "publisher": "American Geophysical Union", "publication": "Journal of Geophysical Research", "publication_date": "1965-02-15", "series_number": "4", "volume": "70", "issue": "4", "pages": "907-922" }, { "id": "authors:48smn-wzh74", "collection": "authors", "collection_id": "48smn-wzh74", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20151021-150137211", "type": "article", "title": "Determination of source parameters of explosions and earthquakes by amplitude equalization of seismic surface waves: 1. Underground nuclear explosions", "author": [ { "family_name": "Toks\u00f6z", "given_name": "M. N.", "clpid": "Toks\u00f6z-M-N" }, { "family_name": "Ben-Menahem", "given_name": "A.", "clpid": "Ben-Menahem-A" }, { "family_name": "Harkrider", "given_name": "D. G.", "clpid": "Harkrider-D-G" } ], "abstract": "A method of determining the source parameters of explosions and earthquakes from the amplitude spectrums of seismic surface waves is described. The method, called amplitude equalization, involves the correction of the ground displacement spectrum for the propagation effect. This is accomplished by multiplying it numerically with the inverse of the frequency response of the layered medium. The result is the amplitude spectrum of the source function, which may be interpreted by itself or jointly with the initial phase spectrum to determine the source-time variation. The spectrums of the Rayleigh waves from underground nuclear explosions are compared and the source-time function is interpreted using the amplitude equalization method. The time variation of the pressure pulse at the boundary of the elastic zone is found to be of the form p(t) = P_0te^(\u2212\u03b7t), where \u03b7 is a parameter which depends on the yield of the explosion and on the medium. For the events studied, the breadth of the pulse increased (\u03b7 decreased) with the yield of the explosion.", "doi": "10.1029/JZ069i020p04355", "issn": "0148-0227", "publisher": "American Geophysical Union", "publication": "Journal of Geophysical Research", "publication_date": "1964-10-15", "series_number": "20", "volume": "69", "issue": "20", "pages": "4355-4366" }, { "id": "authors:63f1p-r8e53", "collection": "authors", "collection_id": "63f1p-r8e53", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140811-110817900", "type": "article", "title": "Mode-ray duality", "author": [ { "family_name": "Ben-Menahem", "given_name": "Ari", "clpid": "Ben-Menahem-A" } ], "abstract": "Earlier results in the theory of terrestrial radio waves are applied to seismology. A partial field of the complete eigen-value solution for a sphere can be interpreted as real rays. Watson's transformation and the WKBJ approximation are employed to establish links between the index trio (l, m, n) of a mode and the corresponding parameters of the ray trajectory associated with this mode. It is shown that Snell's law for rays and Jean's formula are complementary. The condition of constructive interference is expressed as an integral equation for the eigen-frequencies _n\u03c9_l.", "doi": "10.1785/BSSA05405A1315", "issn": "0037-1106", "publisher": "Seismological Society of America", "publication": "Bulletin of the Seismological Society of America", "publication_date": "1964-10", "series_number": "5A", "volume": "54", "issue": "5A", "pages": "1315-1321" }, { "id": "authors:1hfzn-vqs23", "collection": "authors", "collection_id": "1hfzn-vqs23", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140811-111240580", "type": "article", "title": "Spectral response of an elastic sphere to dipolar point-sources", "author": [ { "family_name": "Ben-Menahem", "given_name": "Ari", "clpid": "Ben-Menahem-A" } ], "abstract": "A stratified elastic sphere is excited by an harmonic dipolar source of arbitrary orientation and depth. The total field is expanded in series of vector spherical harmonics and then condensed into a convenient form of a displacement dyadic. The Haskell-Gilbert matrix method is employed to obtain the radial factor of the displacements for a multilayered sphere. The dependence of the field on the azimuth angle and the fault elements is obtained for the case of a double-couple at depth. Expressions are also developed for the radiation pattern of surface waves over a spherical stratified earth.", "doi": "10.1785/BSSA05405A1323", "issn": "0037-1106", "publisher": "Seismological Society of America", "publication": "Bulletin of the Seismological Society of America", "publication_date": "1964-10", "series_number": "5A", "volume": "54", "issue": "5A", "pages": "1323-1340" }, { "id": "authors:9t56a-rkz44", "collection": "authors", "collection_id": "9t56a-rkz44", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20160224-080724513", "type": "article", "title": "Radiation patterns of seismic surface waves from buried dipolar point sources in a flat stratified Earth", "author": [ { "family_name": "Ben-Menahem", "given_name": "Ari", "clpid": "Ben-Menahem-A" }, { "family_name": "Harkrider", "given_name": "David G.", "clpid": "Harkrider-D-G" } ], "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.", "doi": "10.1029/JZ069i012p02605", "issn": "0148-0227", "publisher": "American Geophysical Union", "publication": "Journal of Geophysical Research", "publication_date": "1964-06-15", "series_number": "12", "volume": "69", "issue": "12", "pages": "2605-2620" }, { "id": "authors:m7xdb-rg122", "collection": "authors", "collection_id": "m7xdb-rg122", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20141110-105534414", "type": "article", "title": "Attenuation of dispersed waves", "author": [ { "family_name": "Knopoff", "given_name": "L.", "clpid": "Knopoff-L" }, { "family_name": "Aki", "given_name": "K.", "clpid": "Aki-K" }, { "family_name": "Archambeau", "given_name": "C. B.", "clpid": "Archambeau-C-B" }, { "family_name": "Ben-Menahem", "given_name": "A.", "clpid": "Ben-Menahem-A" }, { "family_name": "Hudson", "given_name": "J. A.", "clpid": "Hudson-J-A" } ], "abstract": "A measure of the absorption of elastic waves is the specific absorption coefficient 1/Q. In dispersive mediums, whether the dispersion is due to geometry, inhomogeneity, or both, measurements are often made outside the body and the measurements must be interpreted as to the distribution of values of 1/Q within the body. \n\nTwo definitive experiments of this type are those performed using standing waves set up in a confined sample of the body and with waves that propagate through or on the surface of the body. Typical examples of these experiments involve the measurement of the damping coefficient of the free modes of vibration of the earth and the measurement of the attenuation factor of propagating surface waves on the earth. These two types of experiments can themselves be interpreted in terms of dimensionless attenuation factors. We call the dimensionless attenuation factors in the standing wave and propagating wave experiments 1/Q_T and 1/Q_x, defined as the logarithmic decrements \u03c0/QT and \u03c0/Q_x in each experiment. Then in a damped standing wave the amplitude will diminish with time t at a fixed point as exp (\u2212\u03c0t/TQ_T), where T is the period. In a propagating monochromatic wave the amplitude will diminish with distance x as exp (\u2212\u03c0x/cTQ_x), where c is the phase velocity.", "doi": "10.1029/JZ069i008p01655", "issn": "0148-0227", "publisher": "American Geophysical Union", "publication": "Journal of Geophysical Research", "publication_date": "1964-04-15", "series_number": "8", "volume": "69", "issue": "8", "pages": "1655-1657" }, { "id": "authors:03xqy-bnc63", "collection": "authors", "collection_id": "03xqy-bnc63", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140801-160221934", "type": "article", "title": "Source-mechanism from spectra of long-period seismic surface waves.\n 3. The Alaska earthquake of July 10, 1958", "author": [ { "family_name": "Ben-Menahem", "given_name": "Ari", "clpid": "Ben-Menahem-A" }, { "family_name": "Toks\u00f6z", "given_name": "M. Nafi", "clpid": "Toks\u00f6z-M-N" } ], "abstract": "Source-mechanism is derived from amplitude and phase spectra of mantle Love and Rayleigh waves of the Alaska earthquake of July 10, 1958. The signals R_2, R_3, G_2, G_4, G_5 recorded on the Gilman 80\u201390 and the Press-Ewing 30\u201390 seismograph systems at Pasadena, California, are separated, digitized, filtered and Fourier-analyzed. An agreement between theory and observations is obtained for a unilateral fault of 300\u2013350 km, which ruptured with a speed of 3-3.5 km/sec in the direction N40\u00b0W. Fault length is in good agreement with the extent of aftershock distribution in the month of July, 1958, and the time of rupture checks with the duration of an impressive T-phase recorded at Hawaii. The phases of the signals are corrected for propagation, instrumental shift and the source finiteness. Initial phases thus obtained agree on a mechanism of a right double-couple with a unit step-function in time.", "doi": "10.1785/BSSA0530050905", "issn": "0037-1106", "publisher": "Seismological Society of America", "publication": "Bulletin of the Seismological Society of America", "publication_date": "1963-10", "series_number": "5", "volume": "53", "issue": "5", "pages": "905-919" }, { "id": "authors:8e7rd-74f53", "collection": "authors", "collection_id": "8e7rd-74f53", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140801-161553811", "type": "article", "title": "Source mechanism from spectrums of long-period surface waves: 2. The Kamchatka earthquake of November 4, 1952", "author": [ { "family_name": "Ben-Menahem", "given_name": "Ari", "clpid": "Ben-Menahem-A" }, { "family_name": "Toks\u00f6z", "given_name": "M. Nafi", "clpid": "Toks\u00f6z-M-N" } ], "abstract": "Fourier analysis of mantle Love and Rayleigh waves from the source of the Kamchatka earthquake of November 4, 1952, recorded on the Benioff linear strain seismograph at Pasadena, furnished further evidence in support of the moving-source theory. Amplitude and phase spectrums of G_1, G_2, G_3, G_4, R_2, and R_3 were processed to obtain information on the mechanism at the source. Both the directivity and the differential phase agree on a unilateral fault of 700 km which ruptured with a speed of 3 km/sec in the direction N 146\u00b0 W. The fault length is in good agreement with the extent of aftershock distribution in the month of November 1952. The initial phases of Love and Rayleigh waves agree on a mechanism of a right orthogonal double couple with a time dependence which is close to the Heaviside step function.", "doi": "10.1029/JZ068i018p05207", "issn": "0148-0227", "publisher": "American Geophysical Union", "publication": "Journal of Geophysical Research", "publication_date": "1963-09-15", "series_number": "18", "volume": "68", "issue": "18", "pages": "5207-5222" }, { "id": "authors:jxq8n-b7v03", "collection": "authors", "collection_id": "jxq8n-b7v03", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140801-153223415", "type": "article", "title": "Velocities of mantle Love and Rayleigh waves over multiple paths", "author": [ { "family_name": "Toks\u00f6z", "given_name": "M. Nafi", "clpid": "Toks\u00f6z-M-N" }, { "family_name": "Ben-Menahem", "given_name": "Ari", "clpid": "Ben-Menahem-A" } ], "abstract": "Phase velocities of Love waves from five major earthquakes are measured over six great circle paths in the period range of 50 to 400 seconds. For two of the great circle paths the phase velocities of Rayleigh waves are also obtained. The digitized seismograph traces are Fourier analyzed, and the phase spectra are used in determining the phase velocities. Where the great circle paths are close, the phase velocities over these paths are found to be in very good agreement with each other indicating that the measured velocities are accurate and reliable. Phase velocities of Love waves over paths that lie far from each other are different, and this difference is consistent and much greater than the experimental error. From this it is concluded that there are lateral variations in the structure of the earth's mantle. One interpretation of this variation is that the mantle under the continents is different from that under the oceans, since the path with the highest phase velocities is almost completely oceanic. This interpretation, however, is not unique and variations under the oceans and continents are also possible. \n\nGroup velocities are computed from the phase velocities and are also directly measured from the seismograms. The group-velocity curve of Love waves has a plateau between periods of 100 and 300 seconds with a shallow minimum at about 290 seconds. The sources of error in both Fourier analysis and direct time domain methods of phase velocity measurement are discussed.", "doi": "10.1785/BSSA0530040741", "issn": "0037-1106", "publisher": "Seismological Society of America", "publication": "Bulletin of the Seismological Society of America", "publication_date": "1963-07", "series_number": "4", "volume": "53", "issue": "4", "pages": "741-764" }, { "id": "authors:b34rv-fdy65", "collection": "authors", "collection_id": "b34rv-fdy65", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140801-160729185", "type": "article", "title": "Source-mechanism from spectra of long-period seismic surface-waves: 1. The Mongolian earthquake of December 4, 1957", "author": [ { "family_name": "Ben-Menahem", "given_name": "Ari", "clpid": "Ben-Menahem-A" }, { "family_name": "Toks\u00f6z", "given_name": "M. Nafi", "clpid": "Toks\u00f6z-M-N" } ], "abstract": "The Pasadena seismograms of the Mongolian earthquake of December 4, 1957, were studied. Mantle Rayleigh waves R_3, R_4, R5, and R_6 were separated, digitized, filtered, and Fourier-analyzed. After the evaluation of the phase velocities and the absorption coefficients from amplitude ratios R_3/R_5 and R_4/R_6 the directivity was computed from the amplitude ratio of R_3/R_4. A fault of 560 km, with an azimuth of 100\u00b0, and a rupture velocity of 3.5 km/sec gave the best fit to the observed directivity. Auxiliary data from aftershock distribution, initial motions, air waves from the main shock, and geological surveys of the fault area seem to support these findings. The phase spectra of R_3 and R_4 were corrected for the propagation phase and the instrumental phase shift to obtain the initial phases at the source. A rough estimate of the depth of faulting is obtained on the basis of the calculated strain release and observed displacements at the fault.", "doi": "10.1029/JZ067i005p01943", "issn": "0148-0227", "publisher": "American Geophysical Union", "publication": "Journal of Geophysical Research", "publication_date": "1962-05", "series_number": "5", "volume": "67", "issue": "5", "pages": "1943-1955" }, { "id": "authors:e8kxx-ssq33", "collection": "authors", "collection_id": "e8kxx-ssq33", "cite_using_url": "https://resolver.caltech.edu/CaltechAUTHORS:20140801-112344479", "type": "article", "title": "Radiation of seismic surface-waves from finite moving sources", "author": [ { "family_name": "Ben-Menahem", "given_name": "Ari", "clpid": "Ben-Menahem-A" } ], "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 length of faulting from seismic records of a single station.", "doi": "10.1785/BSSA0510030401", "issn": "0037-1106", "publisher": "Seismological Society of America", "publication": "Bulletin of the Seismological Society of America", "publication_date": "1961-07", "series_number": "3", "volume": "51", "issue": "3", "pages": "401-435" } ]