microseismometer

from The Collaborative International Dictionary of English v.0.48

Microseismometer \Mi`cro*seis*mom"e*ter\, n. [Microseism +
   -meter.]
   A seismometer for measuring amplitudes or periods, or both,
   of microseisms. -- {Mi`cro*seis*mom"e*try}, n.
   [Webster 1913 Suppl.]