Near Surface Excitation of the Martian Ground as Measured by Insight
Description:
The InSight mission landed on Mars in November 2018 and deployed for the first time a seismometer, the SEIS instrument, on its surface. For more than two Martian years it recorded several thousands of marsquakes and other seismic events, allowing us to study diurnal and seasonal variations in seismicity to better understand the local atmospheric conditions and characterize the Martian interior. Among the many signals recorded by SEIS is a prominent mode around 2.4 Hz. Possible explanations for this signal include a specific lander mode due to the solar arrays, or a local ground substructure as described notably in Hobiger et al. 2020.
In this study, we test the hypothesis of Hobiger et al. 2020 that the 2.4 Hz dominant background noise and Horizontal to Vertical (H/V) ratio are caused by a seismic low velocity zone between 30m and 75m by simulating the amplitude of the 2.4Hz peak observed during marsquakes and during the quiet Martian night. We generate Green’s functions of the ground substructure for high-incidence-angle teleseismic events and for regional surface sources. Subsequently we test the ground response to these excitations by convolving the simulated sources with the appropriate Green’s functions.
We simulate a teleseismic marsquake at a given distance by superimposing a distance-dependent attenuated random signal that mimics the observed scatter of the Martian crust. Background noise is simulated by generating a signal with the frequency and amplitude characteristics of the InSight day and night pressure data.
We show that the simulated amplitudes of the 2.4Hz signal during teleseismic quakes are consistent with SEIS observations. Furthermore, also consistent with InSight observations, the background noise simulation is visible during the night, but is drowned by the elevated ambient environmental noise during daytime.
To test the link between the numerous 2.4 Hz events and excitation of the lander’s solar array from wind bursts, a coupled model of the excitation of the InSight Lander and the subsurface structure will be needed.
Session: Planetary Seismology - I
Type: Oral
Date: 5/1/2024
Presentation Time: 04:30 PM (local time)
Presenting Author: Laurent
Student Presenter: No
Invited Presentation:
Authors
Laurent Pou Presenting Author Corresponding Author sophal.l.pou@jpl.nasa.gov Jet Propulsion Laboratory, California Institute of Technology |
Mark Panning mark.p.panning@jpl.nasa.gov Jet Propulsion Laboratory, California Institute of Technology |
Sharon Kedar sharon.kedar@jpl.nasa.gov Jet Propulsion Laboratory, California Institute of Technology |
Simon Stähler simon.staehler@erdw.ethz.ch ETH Zurich |
Nikolaj Dahmen nikolaj.dahmen@erdw.ethz.ch ETH Zurich |
Nicolas Schmerr nschmerr@umd.edu University of Maryland |
Cedric Schmelzbach cedric.schmelzbach@erdw.ethz.ch ETH Zurich |
Don Banfield banfield@astro.cornell.edu Cornell University |
Naomi Murdoch naomi.murdoch@isae-supaero.fr Université de Toulouse |
Alexander Stott alexander.stott@isae-supaero.fr Université de Toulouse, Toulouse, , France |
Ralph D Lorenz Ralph.Lorenz@jhuapl.edu John Hopkins University, Laurel, Maryland, United States |
Philippe H Lognonné lognonne@ipgp.fr Université Paris Cité, Paris, , France |
William B Banerdt william.b.banerdt@jpl.nasa.gov Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, United States |
Near Surface Excitation of the Martian Ground as Measured by Insight
Category
Planetary Seismology