High frequency seismic events on Mars observed by InSight

Martin van Driel*, Savas Ceylan, John Clinton, D. Giardini, Anna C Horleston, Ludovic Margerin, Simon C. Stähler, Maren Böse, C. Charalambous, Taichi Kawamura, Amir Khan, Guenolé Orhand-Mainsant, John-Robert Scholz, Fabian Euchner, Martin Knapmeyer, Nicholas Schmerr, W. T. Pike, P. Lognonné, W. B. Banerdt

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

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Abstract

The seismometer deployed on the surface of Mars as part of the InSight mission (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport) has recorded several hundreds of marsquakes in the first 478 sols after landing. The majority of these are classified as high‐frequency (HF) events in the frequency range from approximately 1 to 10 Hz on Mars' surface. All the HF events excite a resonance around 2.4 Hz and show two distinct but broad arrivals of seismic energy that are separated by up to 450 s. Based on the frequency content and vertical‐to‐horizontal energy ratio, the HF event family has been subdivided into three event types, two of which we show to be identical and only appear separated due to the signal‐to‐noise ratio. We show here that the envelope shape of the HF events is explained by guided Pg and Sg phases in the Martian crust using simple layered models with scattering. Furthermore, the relative travel times between these two arrivals can be related to the epicentral distance, which shows distinct clustering. The rate at which HF events are observed varies by an order of magnitude over the course of one year and cannot be explained by changes of the background noise only. The HF content and the absence of additional seismic phases constrain crustal attenuation and layering, and the coda shape constrains the diffusivity in the uppermost shallow layers of Mars.
Original languageEnglish
Article numbere2020JE006670
Number of pages20
JournalJournal of Geophysical Research: Planets
Volume126
Issue number2
DOIs
Publication statusPublished - 23 Feb 2021

Bibliographical note

Funding Information:
The authors thank the editor Deanne Rogers, two anonymous reviewers, and Francis Nimmo for helpful comments on the manuscript. We acknowledge NASA, CNES, their partner agencies and Institutions (UKSA, SSO, DLR, JPL, IPGP‐CNRS, ETHZ, IC, MPS‐MPG) and the flight operations team at JPL, SISMOC, MSDS, IRIS‐DMC and PDS for providing SEED SEIS data. AK, DG, JC, and SCS acknowledge support from ETHZ through the ETH + funding scheme (ETH+02 19‐1:“Planet Mars”). This work was supported by grants from the Swiss National Supercomputing Center (CSCS) under project ID s922, and the European Research Council (ERC) under the EU’s Horizon 2020 program (grant No. 714069). L.M. acknowledges the financial support from CNES (Insight Participating Scientist Grant) and ANR MAGIS‐19‐CE31‐0008‐05. Visualizations were created with Matplotlib (Hunter, 2007 ), data were processed with NumPy (Oliphant, 2006 ), Scipy (Jones et al., 2001 ), ObsPy (Krischer et al., 2015 ) and custom software developed by gempa GmbH. The numerical wave propagation simulations are based on the Salvus software suite ( mondaic.com , Afanasiev et al., 2019 ). This is InSight Contribution Number 178.

Funding Information:
The authors thank the editor Deanne Rogers, two anonymous reviewers, and Francis Nimmo for helpful comments on the manuscript. We acknowledge NASA, CNES, their partner agencies and Institutions (UKSA, SSO, DLR, JPL, IPGP-CNRS, ETHZ, IC, MPS-MPG) and the flight operations team at JPL, SISMOC, MSDS, IRIS-DMC and PDS for providing SEED SEIS data. AK, DG, JC, and SCS acknowledge support from ETHZ through the ETH?+?funding scheme (ETH+02 19-1:?Planet Mars?). This work was supported by grants from the Swiss National Supercomputing Center (CSCS) under project ID s922, and the European Research Council (ERC) under the EU?s Horizon 2020 program (grant No. 714069). L.M. acknowledges the financial support from CNES (Insight Participating Scientist Grant) and ANR MAGIS-19-CE31-0008-05. Visualizations were created with Matplotlib (Hunter,?2007), data were processed with NumPy (Oliphant,?2006), Scipy (Jones et?al.,?2001), ObsPy (Krischer et?al.,?2015) and custom software developed by gempa GmbH. The numerical wave propagation simulations are based on the Salvus software suite (mondaic.com, Afanasiev et?al.,?2019). This is InSight Contribution Number 178.

Publisher Copyright:
© 2021. American Geophysical Union. All Rights Reserved.

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