@article{b917fce8b790408d83a03e312abd7f5c,
title = "Focal Mechanism Determination of Event S1222a and Implications for Tectonics Near the Dichotomy Boundary in Southern Elysium Planitia, Mars",
abstract = "On 4 May 2022 the InSight seismometer SEIS-VBB recorded the largest marsquake ever observed, S1222a, with an initial magnitude estimate of (Figure presented.) 4.6. Understanding the depth and source properties of this event has important implications for the nature of tectonic activity on Mars. Located ∼37° to the southeast of InSight, S1222a is one of the few non-impact marsquakes that exhibits prominent surface waves. We use waveform modeling of body waves (P and S) and surface waves (Rayleigh and Love) to constrain the focal mechanism, assuming a double-couple source, and find that S1222a likely resulted from reverse faulting in the crust (source depth near 22 km). We estimate the scalar moment to be 2.5 × 1015–3.5 × 1015 Nm (magnitude MW 4.2–4.3). Our results suggest active compressional tectonics near the dichotomy boundary on Mars, likely due to thermal contraction from planetary cooling.",
keywords = "InSight, Martian tectonics, S1222a, focal mechanism, marsquakes, moment tensor inversion",
author = "R. Maguire and V. Leki{\'c} and D. Kim and N. Schmerr and J. Li and C. Beghein and Q. Huang and Irving, {J. C.E.} and F. Karakostas and P. Lognonn{\'e} and St{\"a}hler, {S. C.} and Banerdt, {W. B.}",
note = "Our moment tensor inversion was based on a modified version of the MTUQ code package (https://github.com/uafgeotools/mtuq), and we thank the developers for making this tool openly available. Seismic data from the S1222a event, and other marsquakes, are available for download through the IRIS Data Management Center. This paper is InSight contribution number 290. The authors acknowledge the NASA, the CNES, their partner agencies and Institutions (UKSA, SSO, DLR, JPL, IPGP-CNRS, ETHZ, IC, and MPS-MPG) and the flight operations team at JPL, SISMOC, MSDS, IRIS-DMC, and PDS for providing the SEED SEIS data. D.K. acknowledges support from the ETH+ funding scheme (ETH+02 19-1: “Planet Mars”). N.S. and V.L. were supported by NASA Grant 80NSSC18K1628. C.B. and J.L. were funded by NASA InSight PSP Grant 80NS-SC18K1679. P.L acknowledges support from CNES and ANR (ANR-19-CE31-0008-08 MAGIS, ANR-18-IDEX-0001). JCEI acknowledges support from UKSA Grant ST/W002515/1. We thank G{\"o}ran Ekstr{\"o}m and Julien Thurin for their thorough and constructive reviews that helped improve this manuscript. Our moment tensor inversion was based on a modified version of the MTUQ code package ( https://github.com/uafgeotools/mtuq ), and we thank the developers for making this tool openly available. Seismic data from the S1222a event, and other marsquakes, are available for download through the IRIS Data Management Center. This paper is InSight contribution number 290. The authors acknowledge the NASA, the CNES, their partner agencies and Institutions (UKSA, SSO, DLR, JPL, IPGP‐CNRS, ETHZ, IC, and MPS‐MPG) and the flight operations team at JPL, SISMOC, MSDS, IRIS‐DMC, and PDS for providing the SEED SEIS data. D.K. acknowledges support from the ETH+ funding scheme (ETH+02 19‐1: “Planet Mars”). N.S. and V.L. were supported by NASA Grant 80NSSC18K1628. C.B. and J.L. were funded by NASA InSight PSP Grant 80NS‐SC18K1679. P.L acknowledges support from CNES and ANR (ANR‐19‐CE31‐0008‐08 MAGIS, ANR‐18‐IDEX‐0001). JCEI acknowledges support from UKSA Grant ST/W002515/1. We thank G{\"o}ran Ekstr{\"o}m and Julien Thurin for their thorough and constructive reviews that helped improve this manuscript.",
year = "2023",
month = sep,
doi = "10.1029/2023JE007793",
language = "English (US)",
volume = "128",
journal = "Journal of Geophysical Research: Planets",
issn = "2169-9097",
publisher = "Wiley-Blackwell",
number = "9",
}