NASA Logo, National Aeronautics and Space Administration
NASA Space Science Data Coordinated Archive Header

Active Seismic Event Data


Availability: At NSSDC, Ready for Offline Distribution (or Staging if Digital)

Time span: 1972-04-21 to 1972-05-23


This data set consists of a magnetic tape of the geophone-recorded seismic signals generated by three grenades fired from a mortar activated by a signal from earth and 19 small explosions created by a thumper activiated by the astronauts. The data are reformatted log-compressed tapes. Ten seconds of seismic data are recorded for each thumper firing. The thumper firings within 15 m of a geophone have impulsive beginnings, and as the distance increase, the seismic signals have more emergent beginnings. The predominent frequency of the thumper is 22 Hz. Up to 41 m little difficulty exists in selecting the onset of the seismic signals, but at greater distances the more emergent onset creates uncertainty in determining the beginning of the seismic wave arrival. The grenade launchings produce a seismic signal detected by the AS E geophones. The seismic records are noisy prior to the onset of impact because launching signals did not completely decay to prefiring conditions. The desired signal can be recognized by a change in frequency, as the power spectra for the impact signals have a predominant signal frequency of 10 Hz compared with 15 to 20 Hz for the grenade launch signal. As the launch signals are closely reproducible from launch to launch, a simple noise subtraction process can also be used. A signal caused by the thrust of the LM ascent engine was also recorded. Most of this signal is concentrated in the frequency band from 5 to 8. The binary magnetic tape was created on a UNIVAC 1108 computer.

Alternate Names


    • Planetary Science: Geology and Geophysics


    • 72-031C-02A

    Additional Information



    Questions and comments about this data collection can be directed to: Coordinated Request and User Support Office



    NameRoleOriginal AffiliationE-mail
    Dr. Robert L. KovachData ProviderStanford
    Dr. Robert L. KovachGeneral ContactStanford
    [] NASA Logo -