Analysis of Synthetic Seismograms for Low-Angle Thrust Faults on Titan
- John Owens,
- Philip Carpenter
Abstract
Little is known of the structure and seismic nature of icy satellites,
planetary bodies that have an outer shell of ice instead of a rocky
crust. One such body, Saturn's moon Titan, is unique because of its
thick atmosphere, hydrologic cycle similar to Earth's, and salty
subsurface ocean. The Dragonfly mission, set to launch in 2026, will use
a robotic rotorcraft to transport various instruments, including a
seismometer, to the Shangri-La dune field on Titan. Until then, Titan's
seismic regime can be estimated by simulating wave propagation through
assumed layering using source models. Ridge belts with low slope angles
suggest fold-and-thrust belts possibly caused by fluid overpressures in
Titan's icy shell. These have been observed in synthetic aperture radar
images from Cassini and may be a likely site for Titan-quakes. Synthetic
seismograms are calculated for Titan-quakes using Instaseis, a
Python-based software sourced by Green's function databases computed by
the axisymmetric spectral element method. Back-azimuth angles are
calculated for different source-receiver configurations. Very high
amplitude waves are interpreted as surface waves. The PP wave is the
first arrival at distances greater than 35 degrees. At 45 degrees, S
waves are not distinguishable.