Knapmeyer et al., Seasonal Seismic Activity on Mars, v 3.1.5, last saved 15/02/2021 16:44:00 ZENODO documentation copy Seasonal Seismic Activity on Mars M. Knapmeyera, S. C. Stählerb, I. Daubarc, F. Forgetd, A. Spigad, T. Pierrond, M. van Drielb, D. Banfielde, E. Haubera, M. Grotta, N. Müllera, C. Perrinp, A. Jacobf, A. Lucasf, B. Knapmeyer-Endrung, C. Newmanh, M. P. Panningi, R. C. Weberj, F. J. Calefi, M. Böseb,r, S. Ceylanb, C. Charalambousk, J. Clintonr, N. Dah- menb, D. Giardinib, A. Horlestonl, T. Kawamuraf, A. Khanb, G. Mainsantq, M. Plasmanf, M. Lemmonn, R. Lorenzo, W. T. Pikek, J.-R. Scholzm, P. Lognonnéf, B. Banerdti Corresponding Author: Martin Knapmeyer DLR Institute for Planetary Research Rutherfordstr. 2 12489 Berlin [email protected] phone: 0049-30-67055394 Affiliations: a Institute of Planetary Research, DLR, Rutherfordstr. 2, 12489 Berlin, Germany. b Institute of Geophysics, ETH Zürich, Sonneggstrasse 5, 8092 Zürich, Switzerland c Department of Earth, Environmental, and Planetary Sciences, Brown University, Campus Box 1846, Provi- dence, RI 02912-1846, USA d Laboratoire de Météorologie Dynamique / Institut Pierre Simon Laplace (LMD/IPSL), Sorbonne Université, Centre National de la Recherche Scientifique (CNRS), École Polytechnique, École Normale Supérieure, France e Cornell University, Cornell Center for Astrophysics and Planetary Science, Ithaca, NY, 14853, USA f Université de Paris, Institut de physique du globe de Paris, CNRS, F-75005 Paris, France g Bensberg Observatory, University of Cologne, Vinzenz-Pallotti-Str. 26, 51429 Bergisch Gladbach, Germany h Aeolis Research, 333 N Dobson Road, Unit 5, Chandler AZ 85224-4412, USA i Jet Propulsion Laboratory, California Institute of Technology; 4800 Oak Grove Dr., M/S 183-301, Pasadena, CA 91109, USA j NASA MSFC, NSSTC Mail Code ST13, 320 Sparkman Drive, Huntsville, AL 35805, USA k Department of Electrical and Electronic Engineering, Imperial College London, South Kensington Campus, London, SW7 2AZ, United Kingdom l School of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol BS8 1RJ, UK m Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany n Space Science Institute, 4765 Walnut Street, Suite B, Boulder, CO 80301, USA o Johns Hopkins Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, USA p Laboratoire de Planétologie et Géodynamique, UMR6112, OSUNA UMS3271, Univ. Nantes, Univ. Angers, CNRS, 2 rue de la Houssinière, BP 92208, 44322 Nantes Cedex 3, France q Institut Supérieur de l'Aéronautique et de l'Espace SUPAERO, 10 Avenue Edouard Belin, 31400 Toulouse, France r Swiss Seismological Service (SED), ETH Zurich, Sonneggstr. 5, 8092 Zurich, Switzerland page 1 of 2 Knapmeyer et al., Seasonal Seismic Activity on Mars, v 3.1.5, last saved 15/02/2021 16:44:00 ZENODO documentation copy About this Document This document contains the paper highlights, graphical abstract, main manuscript, and supplemental information of the paper "Seasonal Seismic Activity on Mars" as submitted to Earth and Planetary Science Letters on 15. February 2021. Highlights: • InSight SEIS finds seasonal variations of "High Frequency" type Marsquake occurrence • Likely driving forces are solar illumination, solar tides, or the CO2 ice cycle • No relation to the orbital periods of Phobos and related tides is found Graphical Abstract page 2 of 2 Knapmeyer et al., Seasonal Seismic Activity on Mars, v 3.1.209, last saved 15/02/2021 09:46:00 For submission to EPSL 1 Seasonal Seismic Activity on Mars 2 M. Knapmeyera, S. C. Stählerb, I. Daubarc, F. Forgetd, A. Spigad, T. Pierrond, M. van Drielb, D. Banfielde, 3 E. Haubera, M. Grotta, N. Müllera, C. Perrinp, A. Jacobf, A. Lucasf, B. Knapmeyer-Endrung, C. Newmanh, 4 M. P. Panningi, R. C. Weberj, F. J. Calefi, M. Böseb,r, S. Ceylanb, C. Charalambousk, J. Clintonr, N. Dah- 5 menb, D. Giardinib, A. Horlestonl, T. Kawamuraf, A. Khanb, G. Mainsantq, M. Plasmanf, M. Lemmonn, R. 6 Lorenzo, W. T. Pikek, J.-R. Scholzm, P. Lognonnéf, B. Banerdti 7 Corresponding Author: 8 Martin Knapmeyer 9 DLR Institute for Planetary Research 10 Rutherfordstr. 2 11 12489 Berlin 12 [email protected] 13 phone: 0049-30-67055394 14 Affiliations: 15 a Institute of Planetary Research, DLR, Rutherfordstr. 2, 12489 Berlin, Germany. 16 b Institute of Geophysics, ETH Zürich, Sonneggstrasse 5, 8092 Zürich, Switzerland 17 c Department of Earth, Environmental, and Planetary Sciences, Brown University, Campus Box 1846, Provi- 18 dence, RI 02912-1846, USA 19 d Laboratoire de Météorologie Dynamique / Institut Pierre Simon Laplace (LMD/IPSL), Sorbonne Université, 20 Centre National de la Recherche Scientifique (CNRS), École Polytechnique, École Normale Supérieure, France 21 e Cornell University, Cornell Center for Astrophysics and Planetary Science, Ithaca, NY, 14853, USA 22 f Université de Paris, Institut de physique du globe de Paris, CNRS, F-75005 Paris, France 23 g Bensberg Observatory, University of Cologne, Vinzenz-Pallotti-Str. 26, 51429 Bergisch Gladbach, Germany 24 h Aeolis Research, 333 N Dobson Road, Unit 5, Chandler AZ 85224-4412, USA 25 i Jet Propulsion Laboratory, California Institute of Technology; 4800 Oak Grove Dr., M/S 183-301, Pasadena, 26 CA 91109, USA 27 j NASA MSFC, NSSTC Mail Code ST13, 320 Sparkman Drive, Huntsville, AL 35805, USA 28 k Department of Electrical and Electronic Engineering, Imperial College London, South Kensington Campus, 29 London, SW7 2AZ, United Kingdom 30 l School of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol BS8 1RJ, UK 31 m Max Planck Institute for Solar System Research, Justus-von-Liebig-Weg 3, 37077 Göttingen, Germany page 1 of 39 Knapmeyer et al., Seasonal Seismic Activity on Mars, v 3.1.209, last saved 15/02/2021 09:46:00 For submission to EPSL 32 n Space Science Institute, 4765 Walnut Street, Suite B, Boulder, CO 80301, USA 33 o Johns Hopkins Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723, USA 34 p Laboratoire de Planétologie et Géodynamique, UMR6112, OSUNA UMS3271, Univ. Nantes, Univ. Angers, 35 CNRS, 2 rue de la Houssinière, BP 92208, 44322 Nantes Cedex 3, France 36 q Institut Supérieur de l'Aéronautique et de l'Espace SUPAERO, 10 Avenue Edouard Belin, 31400 Toulouse, 37 France 38 r Swiss Seismological Service (SED), ETH Zurich, Sonneggstr. 5, 8092 Zurich, Switzerland 39 page 2 of 39 Knapmeyer et al., Seasonal Seismic Activity on Mars, v 3.1.209, last saved 15/02/2021 09:46:00 For submission to EPSL 40 Abstract 41 The activity of High Frequency (HF) marsquakes, as recorded by InSight at Homestead Hollow, Elysium 42 Planitia, increased after about 퐿푆 = 33°, and ceased almost completely by 퐿푆 = 187°, following an ap- 43 parently seasonal variation with a peak rate near aphelion. We define seismic rate models based on the 44 declination of the Sun, annual solar tides, and the annual CO2 cycle as measured by atmospheric pres- 45 sure. Evaluation of Akaike weights and evidence ratios shows that the declination of the Sun is the most 46 likely, and the CO2 cycle the least likely driver of this seismic activity, although the discrimination is weak, 47 and the occurrence of a few events in August 2020 is in favor for a triggering by CO2 ice load. We also 48 show that no periodicity related to Phobos’ orbit is present in the HF event sequence. Event rate fore- 49 casts are presented to allow further discrimination of candidate mechanisms from future observations. 50 Keywords: 51 Mars 52 Elysium Planitia 53 InSight 54 Seasonal Seismic Activity 55 Phobos 56 page 3 of 39 Knapmeyer et al., Seasonal Seismic Activity on Mars, v 3.1.209, last saved 15/02/2021 09:46:00 For submission to EPSL 57 1. Introduction 58 NASA’s InSight (Interior exploration using Seismic Investigations, Geodesy, and Heat Transport) mis- 59 sion, launched in May 2018, landed at a site in the western part of Elysium Planitia, about 500 km to the 60 north of the dichotomy boundary. The landing site is 1500 km west of Cerberus Fossae, which was sus- 61 pected to be seismically active by Taylor et al. (2013). After the touchdown on 26. Nov. 2018, deploy- 62 ment of the seismometer experiment SEIS (Seismic Experiment for Interior Structure; Lognonné et al., 63 2019, 2020) was completed on sol 70 (the 70th Martian day of the mission). SEIS started continuous re- 64 cording on sol 73 (09. Feb. 2019), and reached full performance on sol 85 (21. Feb. 2019, Banerdt et al., 65 2020). With the exception of a downtime from 28. Aug. 2019 to 18. Sep. 2019 (sol 267 to 288; due to a 66 minor problem in power management, which was extended to three weeks duration by the solar con- 67 junction), and a few smaller data losses due to downlink interruptions, SEIS has been recording seismic 68 data continuously ever since. 69 Estimates of the seismic activity of Mars published prior to the InSight mission basically assumed that 70 marsquakes would occur in the same fashion as earthquakes: according to a Gutenberg-Richter distribu- 71 tion in size, and randomly in time (Phillips, 1991, Knapmeyer et al., 2006, Taylor et al., 2013, Plesa et al., 72 2018, and references therein). A certain class of events (High Frequency (HF) and 2.4Hz events, the latter 73 being small HF events visible only by their excitation of an ambient resonance at 2.4 Hz, Clinton et al., 74 2020), however exhibits an occurrence rate that appears variable in time, as shown in Figure 1 (which we 75 first mentioned in Giardini et al., 2020). We interpret the timing of these events as result of a nonsta- 76 tionary Poisson process (supplemental text S6), and compare it with several time-varying processes in 77 order to identify what might drive the nonstationarity.