Estimation of the Seismic Moment Release Rate of Mars using InSight Seismic Data

Abstract

After the first few months of InSight seismic recordings on Mars, we provide an early estimation of the Martian annual seismic moment release rate. The non-detection of unambiguous events by the Viking seismic experiment constrained the annual moment release rate of Mars to within ten orders of magnitude. Evaluation of visible tectonic structures, as well as geodynamic modeling provide further constraints to narrow down this interval to little more than three orders of magnitude. Assuming that the moment-frequency distribution of Marsquakes follows a distribution similar to that found on Earth and Moon, implying that most of the seismic moment is released in the few largest events, it is possible to estimate the global moment release rate from a small number of events above the completeness threshold of the event catalog. We developed statistical estimators based on the tapered Gutenberg Richter distribution which allow computing estimates with as few as one such event. Evaluation of several real catalogs for Earth and Moon, as well as of 560 million synthetic catalogs worth 2.5 billion years of seismicity, shows the feasibility of the approach. We implemented a Monte Carlo method which evaluates our estimators for Marsquakes recorded by InSight, propagates the uncertainty of the individual event’s magnitudes and finally infers how likely any given combination of distribution parameters reproduces the moment rate estimation to within the observational uncertainty. The resulting probabilities can then be used to challenge existing moment rate models.