Abstract
InSight’s seismometers recorded more than 1300 events. Ninety-eight of
these, named the low-frequency family, show energy predominantly below 1
Hz down to ∼0.125 Hz. The Marsquake Service identified seismic phases
and computed distances for 42 of these marsquakes, 26 of which have
backazimuths. Hence, the locations of the majority of low-frequency
family events remain undetermined. Here, we use an envelope shape
similarity approach to determine event classes and distances, and
introduce an alternative method to estimate the backazimuth. In our
similarity approach, we use the highest quality marsquakes with
well-constrained distance estimates as templates, including the largest
event S1222a, and assign distances to marsquakes with relatively high
signal-to-noise ratio based on their similarities to the template
events. The resulting enhanced catalog allows us to re-evaluate the
seismicity of Mars. We find the Valles Marineris region to be more
active than initially perceived, where only a single marsquake (S0976a)
had previously been located. We relocated two marsquakes using new
backazimuth estimates, which had reported distances of ∼90o, in the SW
of the Tharsis region, possibly at Olympus Mons. In addition, two
marsquakes with little or no S-wave energy have been located in the NE
of the Elysium Bulge. Event epicenters in Cerberus Fossae follow a
North-South trend due to uncertainties in location, while the fault
system is in the NW-SE direction; therefore, these events are
re-projected along the observed fault system.