Passive Seismic Experiment

Latham, Gary V.; Ewing, Maurice; Press, Frank; Sutton, George H.; Dorman, James; Nakamura, Y.; Toksöz, N.; Wiggins, Ralph A.; Derr, John S.; Duennebier, F. K.

doi:10.1126/science.167.3918.455

Cited by 143 publications

(90 citation statements)

References 3 publications

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“…For the ensuing three or four years, all reports on the seismic results were published jointly by the Apollo Seismology Team, summarizing the on-going research on seismicity and internal structure as the seismic network was built up and the data base and analysis ideas increased rapidly. The preliminary science reports (Latham et al, 1969b(Latham et al, , 1970d(Latham et al, , 1971b(Latham et al, , 1972b(Latham et al, , 1972d(Latham et al, , 1973c published by NASA were accompanied by a series of Science articles (Latham et al, 1970a(Latham et al, , 1970b(Latham et al, , 1971aToksbz et al, 1972b;Nakamura et al, 1973) reporting progressively more complete analyses on all aspects of the seismic data.…”

Section: 2 Review Of Previous Workmentioning

confidence: 99%

“…Latham et al, 1971b;Strobach, 1970;Berckhemer, 1970). This conclusion has been confirmed by later research (Dainty et al, 1974a;Dainty < d Toks6z, 1977;Nakamura, 1976Nakamura, , 1977bPines, 1973).…”

Section: Seismogram Characteristicsmentioning

confidence: 99%

“…(The energies of the largest meteorite impacts (Day 134, 1972 andDay 199, 1972) used in this work have been estimated at about 10 18-1019 ergs (Dorman et al, 1978;Latham et al, 1972d), implying crater diameters of less than 0.5 km and resulting excavation depths of less than 100-200 meters.…”

Section: -mentioning

confidence: 99%

“…Period, sec The structure of the lunar crust can be divided into two regions based on scale size. The very near-surface structure, as studied by Cooper et al (1974), Nakamura et al (1975), andMark andSutton (1975) covers the outer two kilometers of the moon, while whole crustal structure studies extend to depths of 60-100 km (Latham et al, 1973b;Toks8z et al, 1972bToks8z et al, , 1974a.…”

mentioning

confidence: 99%

“…The near-surface structure of the moon has been ascertained primarily from the active seismic experiment data (Cooper et al, 1974;Kovach and Watkins, 1973a,b,c;Watkins and Kovach, 1973 (Nakamura et al, 1975;Latham et al, 1972b). In addition, the amplification of the horizontal components of ground motion relative to the vertical components at all the PSE (Passive Seismic Experiment) stations can be explained by the effect of a very-low-velocity surface layer on the ellipsoidal particle motion of Rayleigh waves.…”

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confidence: 99%

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Lunar seismology: The internal structure of the Moon

Goins¹,

Dainty²,

Toksöz³

1981

J. Geophys. Res.

147

104

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Tables A1–A4 and Figures A1–A3 are available with entire articleon microfiche. Order from American Geophysical Union, 2000 Florida Avenue, N.W., Washington, D.C. 20009. Document J81‐003;$1.00. Payment must accompany order. The arrival times of direct P and S waves, measured on seismograms recorded from natural lunar seismic events, have been analyzed using linearized inversion and parameter search methods to simultaneously determine event locations, origin times, and structural parameters (seismic velocities). Polarization‐filtered record section plots are correlated with theoretical travel time curves to identify later phases and obtain additional structural and velocity information. Shear wave amplitudes plotted as a function of distance provide data on the existence and magnitude of seismic velocity gradients in the interior. These studies are used to delineate the structure of the moon below the crust to a depth of about 1100 km. This structure has been divided into an upper and a lower mantle. The upper mantle, from 60‐ to 400‐km depth, has average seismic wave velocities of Vp = 7.70 ±0.15 km/s and Vs = 4.45 ± 0.05 km/s with corresponding Q values (taken from the literature) of Qp ∼ 5000 and Qs ∼ 3000. The shear wave velocity decreases with a negative gradient of at most −6 × 10−4 km/s/km, implying a Vs variation of from 4.57 km/s at 60‐km depth to 4.37 km/s at 400‐km depth; this decrease can be accounted for by increasing temperature, and so no major compositional gradient is required in the upper mantle. A small negative P wave velocity gradient may also be present. Between 400‐ and 480‐km depth there is a transition zone with a sharply decreasing shear wave velocity and possibly an accompanying small decrease in Vp. The dominant shear velocity decrease may occur at a 480‐km interface and may represent a compositional change, although the effects of increased temperature cannot be totally ruled out. The lower mantle extends from 480‐km depth to at least 1100‐km depth; few seismic waves recorded by the lunar network penetrate below 1100 km. The average velocities are Vp = 7.6 ± 0.6 km/s and Vs = 4.2 ± 0.1 km/s. Q values (taken from the literature) are Qp ∼ 1500 and Qs ∼ 1000. Below 1100 km there is some indication that the attenuation may increase still further for shear waves, with Qs dropping to a few hundreds or less. This seismic model of the moon is well constrained, with uncertainties on the above values given explicitly by the analysis methods, and so it serves as a strong control on the present‐day lunar compositional and thermal structure.

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Section: 2 Review Of Previous Workmentioning

confidence: 99%

Section: Seismogram Characteristicsmentioning

confidence: 99%

Section: -mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Lunar seismology: The internal structure of the Moon

Goins¹,

Dainty²,

Toksöz³

1981

J. Geophys. Res.

147

104

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Modeling seismic energy propagation in highly scattering environments

2015

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Meteoroid impacts over millions to billions of years can produce a highly fractured and heterogeneous megaregolith layer on planetary bodies such as the Moon that lack effective surface recycling mechanisms. The energy from seismic events on these bodies undergoes scattering in the fractured layer(s) and generates extensive coda wave trains that follow major seismic wave arrivals. The decay properties of these codas are affected by the planetary body's interior structure. To understand the propagation of seismic waves in such media, we model the transmission of seismic energy in highly scattering environments using an adapted phonon method. In this Monte Carlo simulation approach, we track a large number of seismic wavelets as they leave a source and we record the resulting ground deformation each time a wavelet reaches a surface receiver. Our method provides the first numerical global modeling of 3-D scattering, with user-defined power law distributions of scatterer length scales and frequency-dependent intrinsic attenuation, under the assumption of 1-D background velocity models. We model synthetic signals for simple, but highly scattering interior models and vary the model parameters independently to assess their individual effects on the coda. Results show that the magnitude of the decay times is most affected by the background velocity model, in particular the presence of shallow low-velocity layers, the event source depth, and the intrinsic attenuation level. The decay times are also controlled to a lesser extent by the size-frequency distribution of scatterers, the thickness of the scattering layer, and the impedance contrast at the scatterers.

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Effects of lateral variations in megaregolith thickness on predicted lunar seismic signals

Blanchette-Guertin

Johnson

Lawrence

2015

Geophysical Research Letters

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We use a modified phonon synthetic seismogram method to investigate the effects of laterally varying megaregolith thickness on the propagation of seismic energy and on the resulting seismic signals recorded at various epicentral distances from the source. We show that receivers located in large impact structures, with thin crust and thinner megaregolith, can record seismic signals that are less affected by high levels of scattering. In particular, receivers located away from the basin edge by a distance greater than or equal to the thickness of the surrounding megaregolith can record seismograms in which secondary arrivals containing important information about interior structure can be more readily identified. Seismic sources located beneath the near‐surface scattering layer, such as deep lunar quakes, are also advantageous because the resulting seismograms are less affected by high levels of scattering than those from sources within the scattering layer or surface impacts.

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Passive Seismic Experiment

Cited by 143 publications

References 3 publications

Lunar seismology: The internal structure of the Moon

Lunar seismology: The internal structure of the Moon

Modeling seismic energy propagation in highly scattering environments

Effects of lateral variations in megaregolith thickness on predicted lunar seismic signals

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