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Article Dans Une Revue Journal of Geophysical Research. Planets Année : 2021

First Focal Mechanisms of Marsquakes

Alice Jacob
Nobuaki Fuji
Savas Ceylan
  • Fonction : Auteur
Constantinos Charalambous
Martin van Driel
  • Fonction : Auteur
Anna Horleston
Taichi Kawamura
Mark P Panning
William T Pike
  • Fonction : Auteur

Résumé

Since February 2019, NASA's InSight lander is recording seismic signals on the planet Mars, which, for the first time, allows to observe ongoing tectonic processes with geophysical methods. A number of Marsquakes have been located in the Cerberus Fossae graben system in Elysium Planitia and further west, in the Orcus Patera depression. We present a first study of the focal mechanisms of three well-recorded events (S0173a, S0183a, S0235b) to determine the processes dominating in the source region. We infer for all three events a predominantly extensional setting. Our method is adapted to the case of a single, multicomponent receiver and based on fitting waveforms of P and S waves against synthetic seismograms computed for the initial crustal velocity model derived by the InSight team. We explore the uncertainty due to the single-station limitation and find that even data recorded by one station constrains the mechanisms (reasonably) well. For the events in the Cerberus Fossae region (S0173a, S0235b) normal faulting with a relatively steep dipping fault plane is inferred, suggesting an extensional regime mainly oriented E-W to NE-SW. The fault regime in the Orcus Patera region is not determined uniquely because only the P wave can be used for the source inversion. However, we find that the P and weak S waves of the S0183a event show similar polarities to the event S0173, which indicates similar fault regimes.
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Dates et versions

hal-03519105 , version 1 (10-01-2022)

Identifiants

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Nienke Brinkman, Simon C Stähler, Domenico Giardini, Cédric Schmelzbach, Amir Khan, et al.. First Focal Mechanisms of Marsquakes. Journal of Geophysical Research. Planets, 2021, 126 (4), pp.e2020JE006546. ⟨10.1029/2020je006546⟩. ⟨hal-03519105⟩
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