Is it normal for the geophone to sound like something is loose?

I received my RS 4D yesterday. Is it normal for the geophone to sound like something is loose inside? I haven’t powered it up yet.

The noise you are hearing is the sensitive mass in the geophone. It is that mass that “remains motionless” as the earth moves and generates electric signals that become your seismic signal.

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Thanks @OBSeismo. @kerniew This might be of interest to you as well!:


Great! Thanks much. I was afraid that it had been broken during shipping.

Oh no chance, those geophone are tough!

Have fun Shaking


Absolutely, we are having fun shaking here in Ridgecrest, California.

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I found a great description of a seismometer from the 1970 paper on the Lunar Passive Seismic Experiment (Apollo 11 and 12):

Passive Seismic Experiment
Gary V Latham, Maurice Ewing, Frank Press, George Sutton, James Dorman, Yosio Nakamura, Nafi Toksoz, Ralph W iggins and Robert Kooache

“A seismometer consists simply of a mass free to move in one direction that is suspended by means of a spring or a combination of springs and hinges from a framework The suspended mass is provided with damping to suppress vibrations at the natural frequency of the system The framework rests on the surface whose motions are to be studied and moves with the surface The suspended mass tends to remain fixed in space because of its own inertia while the frame moves around the mass The resulting relative motion between the mass and the frame can be recorded and used to calculate original ground motion if the instrumental constants are known.”

Science, 167 (3918), 455-457


Not to bump a dead thread but here’s a citation and link to the Apollo 14 Preliminary Science Report that contains this language. Really good reading for a rainy day:

Latham, G.V., Ewing, M., Press, F. Sutton, G., Dorman, J., Nakamura, Y., Toksoz, N., Duennebier, F., and Lammlein, D., Manned Spacecraft Center (U.S.). (1971). Passive Seismic Experiment. Apollo 14: Preliminary science report. Washington: Scientific and Technical Information Office, National Aeronautics and Space Administration, 133-160, Accessed 3 October, 2019,

Thanks Ian! Just for reference, Latham, Dorman and Nakamura were my MS advisors at UT Austin 1980!!
I’m glad I didn’t have to write a paper about the seismograms recorded on the Moon. It looks like the first results from Mars Insight show events similar to those on the Moon: Emergent onset and no clear phase arrival times (P, S and surface waves, etc.). Everyone expected to see nice sharp pristine Moon and Mars quakes, and the results look like a snake that swallowed a large rat . . . (Rumbles on the Red Planet)

Clearly we have a lot to learn about our planet neighbors!

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That’s so cool! Giants of seismology!

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