Passive seismic experiment

Reviews of Geophysics, 1974

Natural seismic events have been detected by the long-period seismometers at Apollo stations 16, 14, 15, and 12 at annual rates of 3300, 1700, 800, and 700, respectively, with peak activity at 13-to 14-day intervals. Repetitive moonquakes from 41 hypocenters produce seismograms characteristic of each. About 90% of the long-period signaJs are from these and other numerous, less active hypocenters, and meteoroid impact signals account for the remainder. At each hypocenter, moonquakes occur only within an active period of a few days during a characteristic phase of the monthly lunar tidal cycle. An episode of activity may contain up to four quakes from one hypocenter. Nearly equal numbers of hypocenters are active at opposite phases of the monthly cycle, accounting for the 14-day peaks in total lunar seismic activity. A period of about 206 days in the seismic activity of several of the hypocenters is superimposed on a strong one-to two-year trend where the signal amplitudes decrease to the instrumental detection threshold. A 206-day period with no secular decrease in amplitude is also observed in the total lunar seismic activity, sugge.sting that the total number of active hypocenters does not vary appreciably with time. Moonquake magnitudes range between 0.5 and 1.3 on the Richter scale with a total energy release estimated to be about 10 n ergs annually. With several possible exceptions, the moonquake loci located to date occur in two narrow belts on the near side of the moon. Both belts are 100-300 km wide, about 2000 km long, and 800-1000 km deep, and they lie along great-circle arcs. Seismic data from a far-side focus and a large far-side meteorold impact define the base of the lunar lithosphere at a depth of about 1000 km. In our present model the rigid lithosphere overlies an asthenosphere of reduced rigidity in which present-day partial melting is probable. Tidal deformation presumably leads to critical stress concentrations at the base of the lithosphere, where moonquakes are found to occur. The striking tidal periodicities in the pattern of moonquake occurrence and energy release suggest that tidal energy is the dominant source of energy released as moonquakes. Thus, tidal energy is dissipated by moonquakes in the lithosphere and probably by inelastic processes in the asthenosphere. The low level of seismicity and the absence of shallow seismicity implies that the moon is neither expanding nor contracting at an appreciable rate. The secular accumulation of strain implied by the uniform polarities of moonquake signals may result from weak convection in the asthenosphere or from secular recession of the moon from the earth.

The Moon, 1975

Data relevant to the shallow structure of the Moon obtained at the Apollo seismic stations are compared with previously published results of the active seismic experiments. It is concluded that the lunar surface is covered by a layer of low seismic velocity (Vv -~ 100 m s-l), which appears to be equivalent to the lunar regolith defined previously by geological observations. This layer is underlain by a zone of distinctly higher seismic velocity at all of the Apollo landing sites. The regolith thicknesses at the Apollo 11, 12, and 15 sites are estimated from the shear-wave resonance to be 4.4, 3.7, and 4.4 m, respectively. These thicknesses and those determined at the other Apollo sites by the active seismic experiments appear to be correlated with the age determinations and the abundances of extralunar components at the sites. The Moon 13 (1975) 57-66. All Rights Reserved Copyright © 1975 by D. Reidel Publishing Company, Dordreeht-Holland 58 YOSIO NAKAMURA ET AL.

Space Science Reviews

An international team of researchers gathered, with the support of the International Space Science Institute (ISSI), (1) to review seismological investigations of the lunar interior from the Apollo-era and up until the present and (2) to reassess our level of knowledge and uncertainty on the interior structure of the Moon. A companion paper (Nunn et al. in Space Sci. Rev., submitted) reviews and discusses the Apollo lunar seismic data with the aim of creating a new reference seismic data set for future use by the community. In this study, we first review information pertinent to the interior of the Moon that has become Electronic supplementary material The online version of this article (

Space Science Reviews

Several seismic experiments were deployed on the Moon by the astronauts during the Apollo missions. The experiments began in 1969 with Apollo 11, and continued with Apollo 12, 14, 15, 16 and 17. Instruments at Apollo 12, 14, 15, 16 and 17 remained operational until the final transmission in 1977. These remarkable experiments provide a valuable resource. Now is a good time to review this resource, since the InSight mission is returning seismic data from Mars, and seismic missions to the Moon and Europa are in development from different space agencies. We present an overview of the seismic data available from Electronic Supplementary Material The online repository https://doi.org/10.. For each of these, we outline the instrumentation and the data availability.

Science, 2011

Earth and Planetary Science Letters, 2003

The seismic determinations of the crustal thickness and mantle velocities are key parameters for most geophysical and geochemical lunar studies. We determine a new seismic model of the Moon after a complete independent reprocessing of the Apollo lunar seismic data with determination of arrival times of about 60 natural and artificial lunar quakes, as well as travel times of converted phases at the crust^mantle interface below the Apollo 12 landing site. On the near side in the Procellarum KREEP Terrane, the only major discontinuity compatible with the crustm antle boundary is located around 30 km deep. In this terrane, seismic constraints on the crust and mantle lead to a 30 km thick anorthositic crust and a pyroxenite cold mantle, with a bulk composition of 6.4% Al 2 O 3 , 4.9% CaO and 13.3% FeO. Mantle temperatures are in accordance with profiles obtained from the observed electrical conductivity and exclude a liquid Fe core, while being compatible with a Fe^S liquid core. Our Moon model might be explained by a mixture of a primitive Earth with tholeiitic crust and depleted upper mantle, together with a chondritic enstatitic parent body for the impactor planet. It provides mixture coefficients comparable to those obtained by impact simulation as well as an estimate of bulk U of about 28 ppb, in accordance with the U budget in a 40 km mean thick crust, 700 km thick depleted mantle and a lower undepleted primitive mantle. ß

Zenodo (CERN European Organization for Nuclear Research), 2020

The file contains parameters describing the location of the Apollo passive seismometers, including longitude, latitude, elevation, azimuth of the horizontal seismometer components and distance between stations. The location parameters have been updated using data from Lunar Reconnaissance Orbiter (Wagner et al., 2017). The horizontal components were intended to point north (MH1) and east (MH2). However, S12 and S16 were misaligned. station_parameters.csv station_parameters.README S2-Deep Moonquake Stacks The following files are processed deep moonquake stacks from three independent sources in

2000

Lunar mass variations for the region +/-64° latitude related to composition, structure, isostatic and tectonic development of the crust, mantle, and core were developed using gravity and topography from Lunar Prospector, Clementine, and earlier satellite observations. Computed terrain gravity effects were spectrally correlated with the free-air anomalies to differentiate the terrain-correlated and -decorrelated free-air components. Annihilating terrain gravity effects, obtained by subtracting the terrain-correlated anomalies from the terrain gravity effects, were used to estimate the lunar Moho and crustal thicknesses by least squares inversion assuming compensation by crustal thickness variations. Inversion of the terrain-correlated anomalies obtained a radial adjustment model of the Moho that equilibrates the lunar topography. Terrain-decorrelated anomalies were differentiated into crustal and subcrustal components based on their correlation spectrum with the free-air anomalies. I...

Lunar Science [Working Title]

Currently, the interest in studying the processes occurring in other planets surrounding the Earth is becoming increasingly important. The Moon-satellite planet is the closest to the planet Earth, and therefore, it makes sense to organize a system for studying it first and foremost, incorporating the most advanced ideas about the physics of processes in rock massive, which are also used in terrestrial conditions. In this paper, new ideas on the organization of seismological and deformation monitoring are set out, based on the results obtained for the rock massive of the Earth and the theoretical ideas presented in the works of I. Prigogine and S. Hawking.

Geophysical Research Letters, 1974

Analysis of recent lunar seismic data from distant meteorold impacts, highfrequency teleseismic events and deep moonquakes shows several significant deviations of P-and S-wave travel times from those expected if the lunar interior were homogeneous below the crust. These data are interpreted resulting in a lunar model consisting of at least four and possibly five distinguishable zones: (I) the 50 to 60 km thick crust characterized by seismic velocities appropriate for plagioclase-rich materials, (II) the 250 km thick upper mantle characterized by seismic velocities consistent with an olivine-pyroxene composition, (III) the 500 km thick middle mantle characterized by a high (0.33 -0.36) Poisson's ratio, (IV) the lower mantle characterized by high shear-wave attenuation and possibly (V) a core of radius between 170 and 360 km character-