Abstract
AbstractThe state of seismic activity on Mars is currently unknown. On Earth, coseismic displacement has been observed using visible wavelength images and subpixel coregistration and correlation techniques. We apply this method to Mars with the COSI‐Corr (Co‐registration of Optically Sensed Images and Correlation) software package using High‐Resolution Imaging Science Experiment (HiRISE) images, focusing on part of the Cerberus Fossae fault system. We derive best practices for applying this method to the study of coseismic displacements on Mars. Using a time series of eight overlapping HiRISE images, we achieve pixel coregistration with a mean accuracy of about 1/50 of a pixel. We see no clear evidence for coseismic displacement in this region during a time period of over 8 years. One possible displacement signal (1–2 m of west‐east displacement over a length scale of about 50 m) that has similarities to terrestrial coseismic deformation was dismissed as the result of incomplete correction of steep topography during the coregistration stage. Ancillary observations of recurring slope lineae (RSL) activity in the surrounding fault system offer no supporting evidence for the occurrence of coseismic displacement but do seem to suggest RSL activity that does not fit into previous seasonal timescales. Although it is unlikely that we have observed coseismic displacement in our study area during this time period, the best practice method and the accuracy of our results offer encouragement for future studies. HiRISE, Context Camera, and Color and Stereo Surface Imaging System images can be used to complement and independently verify in situ seismic observations by the InSight (Interior Exploration using Seismic Investigations, Geodesy, and Heat Transport) lander or source location changes from the ExoMars Trace Gas Orbiter spacecraft.
Highlights
The European Space Agency ExoMars Trace Gas Orbiter (TGO; Vago et al, 2015) and the National Aeronautics and Space Administration (NASA) InSight (Interior Exploration using Seismic Investigations, Geodesy, and Heat Transport; Banerdt et al, 2013) missions are both focused on detecting and monitoring active surface processes on Mars
In the along-track direction, the dominant artifact is a 0.5- to 0.75-m amplitude periodic signal with a wavelength of ~0.75 km, which is due to spacecraft jitter, and similar to signals observed in SPOT (Satellite pour l’Observation de la Terre ), ASTER, and Quickbird images of Earth, and High-Resolution Imaging Science Experiment (HiRISE) images of Mars (Ayoub et al, 2008, July)
In the across-track direction, the use of Planetary Data System (PDS) data can cause false east-west displacement steps of about 0.5 to 0.75 m, which are the result of misalignment between the different charge-coupled devices (CCDs) of the HiRISE instrument (Figures 3b and 3d)
Summary
The European Space Agency ExoMars Trace Gas Orbiter (TGO; Vago et al, 2015) and the National Aeronautics and Space Administration (NASA) InSight (Interior Exploration using Seismic Investigations, Geodesy, and Heat Transport; Banerdt et al, 2013) missions are both focused on detecting and monitoring active surface processes on Mars. These missions have different overall goals, they both demonstrate that understanding the present is key to understanding the past. The level of seismicity of Mars has been predicted from studies of faulting (e.g., Golombek, 2002; Golombek et al, 1992), with a possible single event having been possibly found in recently archived data (Lorenz et al, 2017)
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