FOCAL MECHANISMS OF SEISMIC EVENTS ON MARS
DOI:
https://doi.org/10.17721/1728-2713.103.06Keywords:
Marsquake, focal mechanisms, direct problem, seismic moment tensorAbstract
According to data obtained by NASA's InSight mission, Mars appears to be a seismically active planet. In this paper, we focus on two events – S0235b and S1222a, the second of which (May 4, 2022, Mw~4.7) is the strongest of all recorded by the broadband seismic station ELYSE, the only one on Mars. Epicentral distance of S1222a was 37.2°. We determine the focal mechanisms of events using the method based on the model of a point source in an elastic horizontally layered medium. Seismic moment tensor is determined by inversion of high-frequency seismograms calculated by the matrix method for direct waves. The process involves convertion into displacements in the time domain after integration over frequency and wavenumber. The use of only direct P- and S-waves, which are less sensitive to propagation effects than reflected and converted ones, significantly improves accuracy and reliability of the proposed method. For the event S1222a, the match of the synthetic forms of direct waves to the observed ones is demonstrated. A comparative analysis of the focal mechanisms obtained for the S0235b event by inversion of only direct waves and by full direct inversion is also presented.
References
Aki, K., & Richards, P.G. (2002). Qantitative seismology. University Science Books.
Banerdt, W.B., Smrekar, S., Banfield, D., Giardini, D., Golombek, M.P., Johnson, C., et al. (2020). Initial results from the insight mission on Mars. Nature Geoscience, 13 (3), 183–189. https://doi.org/10.1038/s4156-020-0544-y
Brinkman, N., Stähler, S.C., Giardini, D., Schmelzbach, C., Khan, A., Jacob, A, et al. (2021). First focal mechanisms of marsquakes. Journal of Geophysical Research: Planets, 126(4), e2020JE006546. https://doi.org /10.1029/2020JE006546
Ceylan, S., Clinton, J., Giardini, D., Stahler, S.C., Horleston, A., Kawamura, T. et al. (2022). The marsquake catalogue from InSight, sols 01011. Physics of the Earth and Planetary Interiors, 333, 106943. https://doi.org/10.1016/j.pepi.2022.106943
Clinton, J., Ceylan, S., van Driel, M., Giardini, D., Stahler, S.C., Bose, M. et al. (2020). The Marsquake catalogue from Insight, sols 0-478. Physics of the Earth and Planetary Interiors, 310, 106595. https://doi.org/10.1016 /j.pepi.2020.106595
Giardini, D., Lognonné, P., Banerdt, W.B., Pike, W.T., Christensen, U., Ceylan, S. et al. (2020). The seismicity of Mars. Nature Geoscience, 13, 205212. https:/doi.org/10.1038/s41561-020-0539-8
Jacob, A., Plasman, M., Perrin, C., Fuji, N., Lognonné, P., Xu, Z. et al. (2022). Seismic sources of InSight marsquakes and seismotectonic context of Elysium Planitia, Mars. Tectonophysics, 837, 229434. https://doi.org /10.1016/j.tecto.2022.229434
Kawamura, T., Clinton, J.F., Zenhausern, G., Ceylan, S., Horleston, A.C., Dahmen, N.L. (2022). S1222a- the largest Marsquake detected by InSight. Geophysical Research Letters. https://doi: 10.1029/2022GL101543.
Lognonné, P., Banerdt, W., Pike, W.T., Giardini, D., Christensen, U., Garcia, R.F. et al. (2020). Constraints on the shallow elastic and anelastic structure of Mars from InSight seismic data. Nature Geoscience, 13(3), 213220. https//doi.org/10.1038/s41561-020-0536-y
Lognonné, P., Banerdt, W.B., Giardini, D., Pike, W.T., Christensen, U., Laudet, P. et al. (2019). SEIS: Insight's Seismic Experiment for Internal Structure of Mars. Space Science Reviews, 215(1), 12. htps//doi.org/10.1007/s11214018-0574-6
Malytskyy, D. (2016). Mathematical modeling in the tasks of seismology. Naukova dumka [in Ukrainian].
Malytskyy, D., D'Amico, S. (2015). Moment tensor solutions through waveforms inversion, Mistral Service S.a.S., Earth and Enviromental Sciences.
Nissen-Meyer, T., van Driel, M., Stahler, S. C., Hosseini, K., Hempel, S., Auer, L. et al. (2014). AxiSEM: broadband 3-D seismic wavefields in axisymmetric media. Solid Earth, 5(1), 425–445.
van Driel, M., Krischer, L., Stahler, S. C., Hosseini, K., & Nissen-Meyer, T. (2015). Instaseis: Instant global seismograms based on a broadband waveform database. Solid Earth, 6(2), 701–717.
Vavryčuk, V., & Kuhn, D. (2012). Moment tensor in version of waveforms: a two-step time-frequency approach. Geophysical Journal International, 190(3), 1761–1776. https://doi.org/10.1111/j.1365-246X.2012.05592.x
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