Title: Empirical Recurrence Rates for Seismic Signals on Planetary Surfaces,
Abstract: We review the recurrence intervals as a function of ground motion amplitude
at several terrestrial locations, and make the first interplanetary comparison
with measurements on the Moon, Mars, Venus and Titan. This empirical approach
gives an intuitive guide to the relative seismicity of these locations, without
invoking interior models and specific sources: for example a Venera-14
observation of possible ground motion indicates a microseismic environment
mid-way between noisy and quiet terrestrial locations; quiet terrestrial
regions see a peak velocity amplitude in mm/s roughly equal to 0.4*N(-0.7),
where N is the number of events observed per year. The Apollo data show signals
for a given recurrence rate are typically about 10,000 times smaller in
amplitude than a quiet site on Earth, while Viking data masked for low-wind
periods appears comparable with a quiet terrestrial site. Recurrence rate plots
from in-situ measurements provide a convenient guide to expectations for
seismic instrumentation on future planetary missions : while small geophones
can discriminate terrestrial activity rates, observations with guidance
accelerometers are typically too insensitive to provide meaningful constraints
unless operated for long periods.