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2. A Re-examination of Ellipticity Corrections for Seismic Phases

Author

Russell, Stuart, Rudge, John F., Irving, Jessica C. E., and Cottaar, Sanne

Subjects
Physics - Geophysics
Abstract

The Earth's ellipticity of figure has an effect on the travel times of seismic waves over teleseismic distances. Tables of ellipticity corrections and coefficients have been used by seismologists for several decades, however due to the increasing variety and complexity of seismic phases in use, current tables of ellipticity coefficients are now outmoded and incomplete. We present a Python package, EllipticiPy, for the calculation of ellipticity corrections that removes the dependence on pre-calculated coefficients at discrete source depths and epicentral distances. EllipticiPy also facilitates the calculation of ellipticity corrections on other planetary bodies. When applied to both Earth and Mars, the magnitudes of ellipticity corrections are on the order of single seconds and are significant for some seismic studies on Earth but remain negligible on Mars due to other greater sources of uncertainty., Comment: Main paper of 11 pages, 4 figures and 1 table plus a supplement of 12 pages and 1 table

Published
2022
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6. Mars from the InSight: Seismology Beyond Earth

Author

Knapmeyer-Endrun, Brigitte, Banerdt, W. Bruce, Smrekar, Suzanne E., Lognonné, Philippe, Giardini, Domenico, Beghein, Caroline, Beucler, Éric, Bozdağ, Ebru, Clinton, John, Garcia, Raphael F., Irving, Jessica C. E., Kawamura, Taichi, Kedar, Sharon, Margerin, Ludovic, Panning, Mark P., Pike, Tom W., Plesa, Ana-Catalina, Schmerr, Nicholas, Teanby, Nicholas, Weber, Renee, Wieczorek, Mark, Barkaoui, Salma, Brinkman, Nienke, Ceylan, Savas, Charalambous, Constantinos, Compaire, Nicolas, Dahmen, Nikolaj, van Driel, Martin, Horleston, Anna, Huang, Quancheng, Hurst, Kenneth, Kenda, Balthasar, Khan, Amir, Kim, Doyeon, Knapmeyer, Martin, Li, Jiaqi, Menina, Sabrina, Murdoch, Naomi, Perrin, Clément, Schimmel, Martin, Stähler, Simon C., Stutzmann, Eléonore, Bezaeva, Natalia S., Series Editor, Gomes Coe, Heloisa Helena, Series Editor, Nawaz, Muhammad Farrakh, Series Editor, Vacareanu, Radu, editor, and Ionescu, Constantin, editor

Published
2022
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8. Initial results from the InSight mission on Mars

Author

Banerdt, W. Bruce, Smrekar, Suzanne E., Banfield, Don, Giardini, Domenico, Golombek, Matthew, Johnson, Catherine L., Lognonné, Philippe, Spiga, Aymeric, Spohn, Tilman, Perrin, Clément, Stähler, Simon C., Antonangeli, Daniele, Asmar, Sami, Beghein, Caroline, Bowles, Neil, Bozdag, Ebru, Chi, Peter, Christensen, Ulrich, Clinton, John, Collins, Gareth S., Daubar, Ingrid, Dehant, Véronique, Drilleau, Mélanie, Fillingim, Matthew, Folkner, William, Garcia, Raphaël F., Garvin, Jim, Grant, John, Grott, Matthias, Grygorczuk, Jerzy, Hudson, Troy, Irving, Jessica C. E., Kargl, Günter, Kawamura, Taichi, Kedar, Sharon, King, Scott, Knapmeyer-Endrun, Brigitte, Knapmeyer, Martin, Lemmon, Mark, Lorenz, Ralph, Maki, Justin N., Margerin, Ludovic, McLennan, Scott M., Michaut, Chloe, Mimoun, David, Mittelholz, Anna, Mocquet, Antoine, Morgan, Paul, Mueller, Nils T., Murdoch, Naomi, Nagihara, Seiichi, Newman, Claire, Nimmo, Francis, Panning, Mark, Pike, W. Thomas, Plesa, Ana-Catalina, Rodriguez, Sébastien, Rodriguez-Manfredi, Jose Antonio, Russell, Christopher T., Schmerr, Nicholas, Siegler, Matt, Stanley, Sabine, Stutzmann, Eléanore, Teanby, Nicholas, Tromp, Jeroen, van Driel, Martin, Warner, Nicholas, Weber, Renee, and Wieczorek, Mark

Published
2020
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10. Mars from the InSight: Seismology Beyond Earth

Author

Knapmeyer-Endrun, Brigitte [0000-0003-3309-6785], Banerdt, W. Bruce [0000-0003-3125-1542], Smrekar, Suzanne E. [0000-0001-8775-075X], Lognonné, Philippe [0000-0002-1014-920X], Giardini, Domenico [0000-0002-5573-7638], Beghein, Caroline [0000-0002-3158-2213], Beucler, Éric [0000-0003-2605-4990], Bozdağ, Ebru 0000-0002-4269-3533`], Clinton, John [0000-0001-8626-2703], Garcia, Raphael F. [0000-0003-1460-6663], Irving, Jessica C. E. [0000-0002-0866-8246], Kawamura, Taichi [0000-0001-5246-5561], Kedar, Sharon [0000-0001-6315-5446], Margerin, Ludovic [0000-0003-4848-3227], Panning, Mark P. [0000-0002-2041-3190], Pike, Tom W. [0000-0002-7660-6231], Plesa, Ana Catalina [0000-0003-3366-7621], Schmerr, Nicholas [0000-0002-3256-1262], Teanby, Nicholas [0000-0003-3108-5775], Weber, Renee [0000-0002-1649-483X], Wieczorek, Mark [0000-0001-7007-4222], Barkaoui, Salma [0000-0001-7266-0815], Brinkman, Nienke [0000-0002-1842-0834], Ceylan, Savas [0000-0002-6552-6850], Charalambous, Constantinos [0000-0002-9139-3895], Compaire, Nicolas [0000-0002-8932-732X], Van Driel, Martin [0000-0002-8938-4615], Horleston, Anna [0000-0002-6748-6522], Huang, Quancheng [0000-0002-5681-5159], Hurst, Kenneth [0000-0002-3822-4689], Kenda, Balthasar [0000-0002-2572-8749], Khan, Amir [0000-0003-4462-3173], Kim, Doyeon [0000-0003-4594-2336], Knapmeyer, Martin [0000-0003-0319-2514], Li, Jiaqi [0000-0001-7525-5401], Menina, Sabrina [0000-0003-1044-6877], Murdoch, Naomi [0000-0002-9701-4075], Perrin, Clément [0000-0002-7200-5682], Schimmel, Martin [0000-0003-2601-4462], Stähler, Simon C. [0000-0002-0783-2489], Stutzmann, Eléonore [0000-0002-4348-7475], Knapmeyer-Endrun, Brigitte, Banerdt, W. Bruce, Smrekar, Suzanne E., Lognonné, Philippe, Giardini, Domenico, Beghein, Caroline, Beucler, Éric, Bozdağ, Ebru, Clinton, John, Garcia, Raphael F., Irving, Jessica C. E., Kawamura, Taichi, Kedar, Sharon, Margerin, Ludovic, Panning, Mark P., Pike, Tom W., Plesa, Ana Catalina, Schmerr, Nicholas, Teanby, Nicholas, Weber, Renee, Wieczorek, Mark, Barkaoui, Salma, Brinkman, Nienke, Ceylan, Savas, Charalambous, Constantinos, Compaire, Nicolas, Dahmen, Nikolaj, van Driel, Martin, Horleston, Anna, Huang, Quancheng, Hurst, Kenneth, Kenda, Balthasar, Khan, Amir, Kim, Doyeon, Knapmeyer, Martin, Li, Jiaqi, Menina, Sabrina, Murdoch, Naomi, Perrin, Clément, Schimmel, Martin, Stähler, Simon C., Stutzmann, Eléonore, Knapmeyer-Endrun, Brigitte [0000-0003-3309-6785], Banerdt, W. Bruce [0000-0003-3125-1542], Smrekar, Suzanne E. [0000-0001-8775-075X], Lognonné, Philippe [0000-0002-1014-920X], Giardini, Domenico [0000-0002-5573-7638], Beghein, Caroline [0000-0002-3158-2213], Beucler, Éric [0000-0003-2605-4990], Bozdağ, Ebru 0000-0002-4269-3533`], Clinton, John [0000-0001-8626-2703], Garcia, Raphael F. [0000-0003-1460-6663], Irving, Jessica C. E. [0000-0002-0866-8246], Kawamura, Taichi [0000-0001-5246-5561], Kedar, Sharon [0000-0001-6315-5446], Margerin, Ludovic [0000-0003-4848-3227], Panning, Mark P. [0000-0002-2041-3190], Pike, Tom W. [0000-0002-7660-6231], Plesa, Ana Catalina [0000-0003-3366-7621], Schmerr, Nicholas [0000-0002-3256-1262], Teanby, Nicholas [0000-0003-3108-5775], Weber, Renee [0000-0002-1649-483X], Wieczorek, Mark [0000-0001-7007-4222], Barkaoui, Salma [0000-0001-7266-0815], Brinkman, Nienke [0000-0002-1842-0834], Ceylan, Savas [0000-0002-6552-6850], Charalambous, Constantinos [0000-0002-9139-3895], Compaire, Nicolas [0000-0002-8932-732X], Van Driel, Martin [0000-0002-8938-4615], Horleston, Anna [0000-0002-6748-6522], Huang, Quancheng [0000-0002-5681-5159], Hurst, Kenneth [0000-0002-3822-4689], Kenda, Balthasar [0000-0002-2572-8749], Khan, Amir [0000-0003-4462-3173], Kim, Doyeon [0000-0003-4594-2336], Knapmeyer, Martin [0000-0003-0319-2514], Li, Jiaqi [0000-0001-7525-5401], Menina, Sabrina [0000-0003-1044-6877], Murdoch, Naomi [0000-0002-9701-4075], Perrin, Clément [0000-0002-7200-5682], Schimmel, Martin [0000-0003-2601-4462], Stähler, Simon C. [0000-0002-0783-2489], Stutzmann, Eléonore [0000-0002-4348-7475], Knapmeyer-Endrun, Brigitte, Banerdt, W. Bruce, Smrekar, Suzanne E., Lognonné, Philippe, Giardini, Domenico, Beghein, Caroline, Beucler, Éric, Bozdağ, Ebru, Clinton, John, Garcia, Raphael F., Irving, Jessica C. E., Kawamura, Taichi, Kedar, Sharon, Margerin, Ludovic, Panning, Mark P., Pike, Tom W., Plesa, Ana Catalina, Schmerr, Nicholas, Teanby, Nicholas, Weber, Renee, Wieczorek, Mark, Barkaoui, Salma, Brinkman, Nienke, Ceylan, Savas, Charalambous, Constantinos, Compaire, Nicolas, Dahmen, Nikolaj, van Driel, Martin, Horleston, Anna, Huang, Quancheng, Hurst, Kenneth, Kenda, Balthasar, Khan, Amir, Kim, Doyeon, Knapmeyer, Martin, Li, Jiaqi, Menina, Sabrina, Murdoch, Naomi, Perrin, Clément, Schimmel, Martin, Stähler, Simon C., and Stutzmann, Eléonore

Abstract

When NASA’s InSight lander touched down in Elysium Planitia, Mars, in November 2018 and deployed its seismometer SEIS, it ushered in a new age for planetary seismology - more than 40 years after the first attempt to record marsquakes with the Viking missions. SEIS, an extremely sensitive instrument, has by now provided near continuous seismic records for more than 3 years. Its rich dataset shows Mars to be seismically active, with over 1,300 marsquakes detected so far, mostly with magnitudes below 4. Despite their small size, these quakes provide important and unprecedented constraints on the interior structure of the planet, from the shallow subsurface via the crust, the lithosphere, and the mantle transition zone down to the core, and allow to study Martian tectonics and thermo-chemical evolution. Single-station seismology has answered some of the big questions about the interior of our planetary neighbour, and this contribution gives an overview of results and surprises so far.

Published
2022

11. First observations of core-Transiting seismic phases on Mars

Author

Université Paris Cité, European Research Council, Irving, Jessica C. E., Lekic, Vedran, Duran, C., Drilleau, M., Kim, D., Rivoldini, A., Khan, A., Samuel, H., Antonangeli, D., Bruce Banerdt, W., Beghein, C., Bozdagk, E., Ceylan, S., Charalambous, C., Clinton, John, Davis, P., García, R., Giardini, Domenico, Catherine Horleston, A., Huang, Q., Hurst, Kenneth J., Kawamura, T., King, S. D., Knapmeyer, M., Li, J., Lognonné, Philippe, Maguire, R., Panning, M.P., Plesa, A.C., Schimmel, Martin, Schmerr, N. C., Stählerc, S. C., Stutzmann, Eléonore, Xu, Z., Université Paris Cité, European Research Council, Irving, Jessica C. E., Lekic, Vedran, Duran, C., Drilleau, M., Kim, D., Rivoldini, A., Khan, A., Samuel, H., Antonangeli, D., Bruce Banerdt, W., Beghein, C., Bozdagk, E., Ceylan, S., Charalambous, C., Clinton, John, Davis, P., García, R., Giardini, Domenico, Catherine Horleston, A., Huang, Q., Hurst, Kenneth J., Kawamura, T., King, S. D., Knapmeyer, M., Li, J., Lognonné, Philippe, Maguire, R., Panning, M.P., Plesa, A.C., Schimmel, Martin, Schmerr, N. C., Stählerc, S. C., Stutzmann, Eléonore, and Xu, Z.

Abstract

We present the first observations of seismic waves propagating through the core of Mars. These observations, made using seismic data collected by the InSight geophysical mission, have allowed us to construct the first seismically constrained models for the elastic properties of Mars core. We observe core-Transiting seismic phase SKS from two farside seismic events detected on Mars and measure the travel times of SKS relative to mantle traversing body waves. SKS travels through the core as a compressional wave, providing information about bulk modulus and density. We perform probabilistic inversions using the core-sensitive relative travel times together with gross geophysical data and travel times from other, more proximal, seismic events to seek the equation of state parameters that best describe the liquid iron-Alloy core. Our inversions provide constraints on the velocities in Mars core and are used to develop the first seismically based estimates of its composition. We show that models informed by our SKS data favor a somewhat smaller (median core radius = 1,780 to 1,810 km) and denser (core density = 6.2 to 6.3 g/cm3) core compared to previous estimates, with a P-wave velocity of 4.9 to 5.0 km/s at the core mantle boundary, with the composition and structure of the mantle as a dominant source of uncertainty. We infer from our models that Mars core contains a median of 20 to 22 wt% light alloying elements when we consider sulfur, oxygen, carbon, and hydrogen. These data can be used to inform models of planetary accretion, composition, and evolution.

Published
2023

13. Seismic detection of a deep mantle discontinuity within Mars by InSight

Author

Huang, Quancheng, primary, Schmerr, Nicholas C., additional, King, Scott D., additional, Kim, Doyeon, additional, Rivoldini, Attilio, additional, Plesa, Ana-Catalina, additional, Samuel, Henri, additional, Maguire, Ross R., additional, Karakostas, Foivos, additional, Lekić, Vedran, additional, Charalambous, Constantinos, additional, Collinet, Max, additional, Myhill, Robert, additional, Antonangeli, Daniele, additional, Drilleau, Mélanie, additional, Bystricky, Misha, additional, Bollinger, Caroline, additional, Michaut, Chloé, additional, Gudkova, Tamara, additional, Irving, Jessica C. E., additional, Horleston, Anna, additional, Fernando, Benjamin, additional, Leng, Kuangdai, additional, Nissen-Meyer, Tarje, additional, Bejina, Frederic, additional, Bozdağ, Ebru, additional, Beghein, Caroline, additional, Waszek, Lauren, additional, Siersch, Nicki C., additional, Scholz, John-Robert, additional, Davis, Paul M., additional, Lognonné, Philippe, additional, Pinot, Baptiste, additional, Widmer-Schnidrig, Rudolf, additional, Panning, Mark P., additional, Smrekar, Suzanne E., additional, Spohn, Tilman, additional, Pike, William T., additional, Giardini, Domenico, additional, and Banerdt, W. Bruce, additional

Published
2022
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16. Global quieting of high-frequency seismic noise due to COVID-19 pandemic lockdown measures

Author

Royal Society (UK), German Research Centre for Geosciences, Boğaziçi Üniversity, Netherlands Organization for Scientific Research, Air Force Office of Scientific Research (US), National Science Foundation (US), Consejo Nacional de Ciencia y Tecnología (México), Universidad Nacional Autónoma de México, Agencia Nacional de Investigación y Desarrollo (Chile), Natural Environment Research Council (UK), University of California, Commonwealth Scientific and Industrial Research Organisation (Australia), Belgian Science Policy Office, Fonds National de la Recherche Luxembourg, Lecocq, Thomas [0000-0002-4988-6477], Hicks, Stephen [0000-0002-7476-3284], Noten, Koen Van [0000-0001-8933-4426], Wijk, Kasper van [0000-0003-4994-8030], Plaen, Raphael de [0000-0003-3477-2001], Massin, Frédérick [0000-0002-7532-5139], Hillers, Gregor [0000-0003-2341-1892], Apoloner, Maria-Theresia [0000-0002-4006-1284], Arroyo-Solórzano, Mario [0000-0002-1653-2680], Assink, Jelle [0000-0002-4990-6845], Büyükakpınar, Pinar [0000-0001-8461-674X], Cannata, Andrea [0000-0002-0028-5822], Cannavó, Flavio [0000-0001-7550-8579], Carrasco, Sebastián [0000-0002-6207-8757], Caudron, Corentin [0000-0002-3748-0007], Chaves, Esteban [0000-0002-5724-1513], Cornwell, David G. [0000-0002-9843-7811], Craig, David [0000-0001-9414-1725], Diaz, J. [0000-0003-1801-0541], Donner, Stefanie [0000-0001-7351-8079], Evangelidis, Christos [0000-0001-8733-8984], Evers, Läslo [0000-0003-2825-6211], Fernández, Gonzalo A. [0000-0001-8284-9566], Giannopoulos, Dimitrios [0000-0002-8314-0759], Gibbons, Steven J. [0000-0002-7822-0244], Girona, Társilo [0000-0001-6422-0422], Grecu, Bogdan [0000-0002-7662-996X], Grunberg, Marc [0000-0002-1307-7790], Hetényi, Gyorgy [0000-0001-9036-4761], Horleston, Anna [0000-0002-6748-6522], Inza, Adolfo [0000-0001-5381-9042], Irving, Jessica C. E. [0000-0002-0866-8246], Jamalreyhani, Mohammadreza [0000-0003-4181-7175], Kafka, Alan [0000-0001-6643-1602], Labedz, Celeste [0000-0001-7339-2170], Lindsey, Nathaniel [0000-0001-9522-6683], McKinno, Mika [0000-0002-9274-0377], Megies, Tobias [0000-0002-5033-9921], Miller, Meghan [0000-0001-5494-2296], Minarik, William [0000-0001-5509-5543], Moresi, Louis [0000-0003-3685-174X], Márquez-Ramirez, V. H. [0000-0003-1494-2229], Möllhoff, Martin [0000-0003-1848-1554], Nesbitt, Ian M. [0000-0001-5828-6070], Niyogi, Shankho [0000-0002-8362-4569], Ojeda, Javier [0000-0002-7188-8356], Oth, Adrien [0000-0003-4859-6504], Proud, Simon [0000-0003-3880-6774], Retailleau, Lise [0000-0002-0711-4540], Satriano, Claudio [0000-0002-3039-2530], Savage, Martha [0000-0002-2080-0676], Shani-Kadmiel, Shahar [0000-0003-2215-6164], Sleeman,Reinoud [0000-0002-1928-5056], Sokos, Efthimios [0000-0002-7742-7251], Stott, Alexander [0000-0001-6121-705X], Subedi, Shiba [0000-0002-7009-7333], Sørensen, Mathilde [0000-0002-8589-7480], Taira, Taka'aki [0000-0002-6170-797X], Turhan, Fatih [0000-0003-4612-7421], Pluijm, Ben van der [0000-0001-7737-2791], Vergne, Jérôme [0000-0003-1731-9360], Vuorinen, Tommi A. T. [0000-0002-8186-012X], Warren, Tristram [0000-0003-3877-0046], Wassermann, Joachim [0000-0002-4088-1792], Xiao, Han [0000-0001-8727-8053], Lecocq, Thomas, Hicks, Stephen, Noten, Koen Van, Wijk, Kasper van, Koelemeijer, Paula, Plaen, Raphael de, Massin, Frédérick, Hillers, Gregor, Anthony, Robert E., Apoloner, Maria-Theresia, Arroyo-Solórzano, Mario, Assink, Jelle, Büyükakpınar, Pinar, Cannata, Andrea, Cannavó, Flavio, Carrasco, Sebastián, Caudron, Corentin, Chaves, Esteban, Cornwell, David G., Craig, David, Ouden, Olivier F. C. den, Diaz, J., Donner, Stefanie, Evangelidis, Christos, Evers, Läslo, Fauville, Benoit, Fernández, Gonzalo A., Giannopoulos, Dimitrios, Gibbons, Steven J., Girona, Társilo, Grecu, Bogdan, Grunberg, Marc, Hetényi, Gyorgy, Horleston, Anna, Inza, Adolfo, Irving, Jessica C. E., Jamalreyhani, Mohammadreza, Kafka, Alan, Koymans, Mathijs R., Labedz, Celeste, Larose, Eric, Lindsey, Nathaniel, McKinno, Mika, Megies, Tobias, Miller, Meghan, Minarik, William, Moresi, Louis, Márquez-Ramirez, V. H., Möllhoff, Martin, Nesbitt, Ian M., Niyogi, Shankho, Ojeda, Javier, Oth, Adrien, Proud, Simon, Pulli, Jay, Retailleau, Lise, Rintamäki, Annukka E., Satriano, Claudio, Savage, Martha, Shani-Kadmiel, Shahar, Sleeman,Reinoud, Sokos, Efthimios, Stott, Alexander, Subedi, Shiba, Sørensen, Mathilde, Taira, Taka'aki, Tapia, Mar, Turhan, Fatih, Pluijm, Ben van der, Vergne, Jérôme, Vuorinen, Tommi A. T., Warren, Tristram, Wassermann, Joachim, Xiao, Han, Royal Society (UK), German Research Centre for Geosciences, Boğaziçi Üniversity, Netherlands Organization for Scientific Research, Air Force Office of Scientific Research (US), National Science Foundation (US), Consejo Nacional de Ciencia y Tecnología (México), Universidad Nacional Autónoma de México, Agencia Nacional de Investigación y Desarrollo (Chile), Natural Environment Research Council (UK), University of California, Commonwealth Scientific and Industrial Research Organisation (Australia), Belgian Science Policy Office, Fonds National de la Recherche Luxembourg, Lecocq, Thomas [0000-0002-4988-6477], Hicks, Stephen [0000-0002-7476-3284], Noten, Koen Van [0000-0001-8933-4426], Wijk, Kasper van [0000-0003-4994-8030], Plaen, Raphael de [0000-0003-3477-2001], Massin, Frédérick [0000-0002-7532-5139], Hillers, Gregor [0000-0003-2341-1892], Apoloner, Maria-Theresia [0000-0002-4006-1284], Arroyo-Solórzano, Mario [0000-0002-1653-2680], Assink, Jelle [0000-0002-4990-6845], Büyükakpınar, Pinar [0000-0001-8461-674X], Cannata, Andrea [0000-0002-0028-5822], Cannavó, Flavio [0000-0001-7550-8579], Carrasco, Sebastián [0000-0002-6207-8757], Caudron, Corentin [0000-0002-3748-0007], Chaves, Esteban [0000-0002-5724-1513], Cornwell, David G. [0000-0002-9843-7811], Craig, David [0000-0001-9414-1725], Diaz, J. [0000-0003-1801-0541], Donner, Stefanie [0000-0001-7351-8079], Evangelidis, Christos [0000-0001-8733-8984], Evers, Läslo [0000-0003-2825-6211], Fernández, Gonzalo A. [0000-0001-8284-9566], Giannopoulos, Dimitrios [0000-0002-8314-0759], Gibbons, Steven J. [0000-0002-7822-0244], Girona, Társilo [0000-0001-6422-0422], Grecu, Bogdan [0000-0002-7662-996X], Grunberg, Marc [0000-0002-1307-7790], Hetényi, Gyorgy [0000-0001-9036-4761], Horleston, Anna [0000-0002-6748-6522], Inza, Adolfo [0000-0001-5381-9042], Irving, Jessica C. E. [0000-0002-0866-8246], Jamalreyhani, Mohammadreza [0000-0003-4181-7175], Kafka, Alan [0000-0001-6643-1602], Labedz, Celeste [0000-0001-7339-2170], Lindsey, Nathaniel [0000-0001-9522-6683], McKinno, Mika [0000-0002-9274-0377], Megies, Tobias [0000-0002-5033-9921], Miller, Meghan [0000-0001-5494-2296], Minarik, William [0000-0001-5509-5543], Moresi, Louis [0000-0003-3685-174X], Márquez-Ramirez, V. H. [0000-0003-1494-2229], Möllhoff, Martin [0000-0003-1848-1554], Nesbitt, Ian M. [0000-0001-5828-6070], Niyogi, Shankho [0000-0002-8362-4569], Ojeda, Javier [0000-0002-7188-8356], Oth, Adrien [0000-0003-4859-6504], Proud, Simon [0000-0003-3880-6774], Retailleau, Lise [0000-0002-0711-4540], Satriano, Claudio [0000-0002-3039-2530], Savage, Martha [0000-0002-2080-0676], Shani-Kadmiel, Shahar [0000-0003-2215-6164], Sleeman,Reinoud [0000-0002-1928-5056], Sokos, Efthimios [0000-0002-7742-7251], Stott, Alexander [0000-0001-6121-705X], Subedi, Shiba [0000-0002-7009-7333], Sørensen, Mathilde [0000-0002-8589-7480], Taira, Taka'aki [0000-0002-6170-797X], Turhan, Fatih [0000-0003-4612-7421], Pluijm, Ben van der [0000-0001-7737-2791], Vergne, Jérôme [0000-0003-1731-9360], Vuorinen, Tommi A. T. [0000-0002-8186-012X], Warren, Tristram [0000-0003-3877-0046], Wassermann, Joachim [0000-0002-4088-1792], Xiao, Han [0000-0001-8727-8053], Lecocq, Thomas, Hicks, Stephen, Noten, Koen Van, Wijk, Kasper van, Koelemeijer, Paula, Plaen, Raphael de, Massin, Frédérick, Hillers, Gregor, Anthony, Robert E., Apoloner, Maria-Theresia, Arroyo-Solórzano, Mario, Assink, Jelle, Büyükakpınar, Pinar, Cannata, Andrea, Cannavó, Flavio, Carrasco, Sebastián, Caudron, Corentin, Chaves, Esteban, Cornwell, David G., Craig, David, Ouden, Olivier F. C. den, Diaz, J., Donner, Stefanie, Evangelidis, Christos, Evers, Läslo, Fauville, Benoit, Fernández, Gonzalo A., Giannopoulos, Dimitrios, Gibbons, Steven J., Girona, Társilo, Grecu, Bogdan, Grunberg, Marc, Hetényi, Gyorgy, Horleston, Anna, Inza, Adolfo, Irving, Jessica C. E., Jamalreyhani, Mohammadreza, Kafka, Alan, Koymans, Mathijs R., Labedz, Celeste, Larose, Eric, Lindsey, Nathaniel, McKinno, Mika, Megies, Tobias, Miller, Meghan, Minarik, William, Moresi, Louis, Márquez-Ramirez, V. H., Möllhoff, Martin, Nesbitt, Ian M., Niyogi, Shankho, Ojeda, Javier, Oth, Adrien, Proud, Simon, Pulli, Jay, Retailleau, Lise, Rintamäki, Annukka E., Satriano, Claudio, Savage, Martha, Shani-Kadmiel, Shahar, Sleeman,Reinoud, Sokos, Efthimios, Stott, Alexander, Subedi, Shiba, Sørensen, Mathilde, Taira, Taka'aki, Tapia, Mar, Turhan, Fatih, Pluijm, Ben van der, Vergne, Jérôme, Vuorinen, Tommi A. T., Warren, Tristram, Wassermann, Joachim, and Xiao, Han

Abstract

Human activity causes vibrations that propagate into the ground as high-frequency seismic waves. Measures to mitigate the COVID-19 pandemic caused widespread changes in human activity, leading to a months-long reduction in seismic noise of up to 50%. The 2020 seismic noise quiet period is the longest and most prominent global anthropogenic seismic noise reduction on record. While the reduction is strongest at surface seismometers in populated areas, this seismic quiescence extends for many kilometers radially and hundreds of meters in depth. This provides an opportunity to detect subtle signals from subsurface seismic sources that would have been concealed in noisier times and to benchmark sources of anthropogenic noise. A strong correlation between seismic noise and independent measurements of human mobility suggests that seismology provides an absolute, real-time estimate of population dynamics.

Published
2020

17. An Autonomous Lunar Geophysical Experiment Package (ALGEP) for future space missions

Author

Kawamura, Taichi, Grott, Matthias, Horleston, Anna C, Teanby, Nicholas A, Irving, Jessica C E, and et, al

Abstract

Geophysical observations will provide key information about the inner structure of the planets and satellites and understanding the internal structure is a strong constraint on the bulk composition and thermal evolution of these bodies. Thus, geophysical observations are a key to uncovering the origin and evolution of the Moon. In this article, we propose the development of an autonomous lunar geophysical experiment package, composed of a suite of instruments and a central station with standardized interface, which can be installed on various future lunar missions. By fixing the interface between instruments and the central station, it would be possible to easily configure an appropriate experiment package for different missions. We describe here a series of geophysical instruments that may be included as part of the geophysical package: a seismometer, a magnetometer, a heat flow probe, and a laser reflector. These instruments will provide mechanical, thermal, and geodetic parameters of the Moon that are strongly related to the internal structure. We discuss the functionality required for future geophysical observations of the Moon, including the development of the central station that will be used commonly by different payloads.

Published
2022

18. Recording earthquakes for tomographic imaging of the mantle beneath the South Pacific by autonomous MERMAID floats

Author

Simon, Joel D, Simons, Frederik J, Irving, Jessica C E, Simon, Joel D, Simons, Frederik J, and Irving, Jessica C E

Abstract

We present the first 16 months of data returned from a mobile array of 16 freely-floating diving instruments, named MERMAID for Mobile Earthquake Recording in Marine Areas by Independent Divers, launched in French Polynesia in late 2018. Our 16 are a subset of the 50 MERMAIDs deployed over a number of cruises in this vast and understudied oceanic province as part of the collaborative South Pacific Plume Imaging and Modeling (SPPIM) project, under the aegis of the international EarthScope-Oceans consortium. Our objective is the hydroacoustic recording, from within the oceanic water column, of the seismic wavefield generated by earthquakes worldwide, and the nearly real-time transmission by satellite of these data, collected above and in the periphery of the South Pacific Superswell. This region, characterized by anomalously elevated oceanic crust and myriad seamounts, is believed to be the surface expression of deeply-rooted mantle upwellings. Tomographically imaging Earth’s mantle under the South Pacific with data from these novel instruments requires a careful examination of the earthquake-to-MERMAID travel times of the high-frequency P-wave detections within the windows selected for reporting by the discrimination algorithms on board. We discuss a workflow suitable for a fast-growing mobile sensor database to pick the relevant arrivals, match them to known earthquakes in global earthquake catalogs, calculate their travel-time residuals with respect to global seismic reference models, characterize their quality, and estimate their uncertainty. We detail seismicity rates as recorded by MERMAID over 16 months, quantify the completeness of our catalog, and discuss magnitude-distance relations of detectability for our network. The projected lifespan of an individual MERMAID is five years, allowing us to estimate the final size of the data set that will be available for future study. To prove their utility for seismic tomography we compare MERMAID data quality against “

Published
2022
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19. Seismic detection of a deep mantle discontinuity within Mars by InSight

Author

Huang, Quancheng, Schmerr, Nicholas C., King, Scott D., Kim, Doyeon, Rivoldini, Attilio, Plesa, Ana-Catalina, Samuel, Henri, Maguire, Ross R., Karakostas, Foivos, Lekić, Vedran, Charalambous, Constantinos, Collinet, Max, Myhill, Robert, Antonangeli, Daniele, Drilleau, Melanie, Bystricky, Misha, Bollinger, Caroline, Michaut, Chloe, Gudkova, Tamara, Irving, Jessica C. E., Horleston, Anna, Fernando, Benjamin, Leng, Kuangdai, Nissen-Meyer, Tarje, Bejina, Frederic, Bozdag, Ebru, Beghein, Caroline, Waszek, Lauren, Siersch, Nicki C., Scholz, John-Robert, Davis, Paul M., Lognonné, Philippe, Pinot, Baptiste, Widmer-Schnidrig, Rudolf, Panning, Mark P., Smrekar, Suzanne E., Spohn, Tilman, Pike, William T., Giardini, Domenico, Banerdt, W. Bruce, Huang, Quancheng, Schmerr, Nicholas C., King, Scott D., Kim, Doyeon, Rivoldini, Attilio, Plesa, Ana-Catalina, Samuel, Henri, Maguire, Ross R., Karakostas, Foivos, Lekić, Vedran, Charalambous, Constantinos, Collinet, Max, Myhill, Robert, Antonangeli, Daniele, Drilleau, Melanie, Bystricky, Misha, Bollinger, Caroline, Michaut, Chloe, Gudkova, Tamara, Irving, Jessica C. E., Horleston, Anna, Fernando, Benjamin, Leng, Kuangdai, Nissen-Meyer, Tarje, Bejina, Frederic, Bozdag, Ebru, Beghein, Caroline, Waszek, Lauren, Siersch, Nicki C., Scholz, John-Robert, Davis, Paul M., Lognonné, Philippe, Pinot, Baptiste, Widmer-Schnidrig, Rudolf, Panning, Mark P., Smrekar, Suzanne E., Spohn, Tilman, Pike, William T., Giardini, Domenico, and Banerdt, W. Bruce

Abstract

Constraining the thermal and compositional state of the mantle is crucial for deciphering the formation and evolution of Mars. Mineral physics predicts that Mars’ deep mantle is demarcated by a seismic discontinuity arising from the pressure-induced phase transformation of the mineral olivine to its higher-pressure polymorphs, making the depth of this boundary sensitive to both mantle temperature and composition. Here, we report on the seismic detection of a midmantle discontinuity using the data collected by NASA’s InSight Mission to Mars that matches the expected depth and sharpness of the postolivine transition. In five teleseismic events, we observed triplicated P and S waves and constrained the depth of this discontinuity to be 1,006 ± 40 km by modeling the triplicated waveforms. From this depth range, we infer a mantle potential temperature of 1,605 ± 100 K, a result consistent with a crust that is 10 to 15 times more enriched in heat-producing elements than the underlying mantle. Our waveform fits to the data indicate a broad gradient across the boundary, implying that the Martian mantle is more enriched in iron compared to Earth. Through modeling of thermochemical evolution of Mars, we observe that only two out of the five proposed composition models are compatible with the observed boundary depth. Our geodynamic simulations suggest that the Martian mantle was relatively cold 4.5 Gyr ago (1,720 to 1,860 K) and are consistent with a present-day surface heat flow of 21 to 24 mW/m2

Published
2022
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20. The Far Side of Mars: Two Distant Marsquakes Detected by InSight

Author

UK Space Agency, Agence Nationale de la Recherche (France), NASA Jet Propulsion Laboratory, Horleston, Anna C., Clinton, John F., Ceylan, S., Giardini, Domenico, Charalambous, C., Irving, Jessica C. E., Lognonné, P., Stähler, S. C., Zenhäusern, Geraldine, Dahmen, N. L., Duran, C., Kawamura, T., Khan, A., Kim, Doyeon, Plasman, Matthieu, Euchner, F., Beghein, Caroline, Beucler, E., Huang, Quancheng, Knapmeyer‐Endrun, Brigitte, Lekic, Vedran, Li, Jiaqi, Perrin, C., Schimmel, Martin, Schmerr, Nicholas C., Stott, A. E., Stutzmann, Éléonore, Teanby, Nicholas A., Xu, Zongbo, Panning, Mark, Banerdt, William B., UK Space Agency, Agence Nationale de la Recherche (France), NASA Jet Propulsion Laboratory, Horleston, Anna C., Clinton, John F., Ceylan, S., Giardini, Domenico, Charalambous, C., Irving, Jessica C. E., Lognonné, P., Stähler, S. C., Zenhäusern, Geraldine, Dahmen, N. L., Duran, C., Kawamura, T., Khan, A., Kim, Doyeon, Plasman, Matthieu, Euchner, F., Beghein, Caroline, Beucler, E., Huang, Quancheng, Knapmeyer‐Endrun, Brigitte, Lekic, Vedran, Li, Jiaqi, Perrin, C., Schimmel, Martin, Schmerr, Nicholas C., Stott, A. E., Stutzmann, Éléonore, Teanby, Nicholas A., Xu, Zongbo, Panning, Mark, and Banerdt, William B.

Abstract

For over three Earth years the Marsquake Service has been analyzing the data sent back from the Seismic Experiment for Interior Structure¿the seismometer placed on the surface of Mars by NASA¿s InSight lander. Although by October 2021, the Mars seismic catalog included 951 events, until recently all these events have been assessed as lying within a radius of 100° of InSight. Here we report two distant events that occurred within days of each other, located on the far side of Mars, giving us our first glimpse into Mars¿ core shadow zone. The first event, recorded on 25 August 2021 (InSight sol 976), shows clear polarized arrivals that we interpret to be PP and SS phases at low frequencies and locates to Valles Marineris, 146° ± 7° from InSight. The second event, occurring on 18 September 2021 (sol 1000), has significantly more broadband energy with emergent PP and SS arrivals, and a weak phase arriving before PP that we interpret as Pdiff¿. Considering uncertain pick times and poorly constrained travel times for Pdiff¿, we estimate this event is at a distance between 107° and 147° from InSight. With magnitudes of MMaw 4.2 and 4.1, respectively, these are the largest seismic events recorded so far on Mars.

Published
2022

21. First observations of core-transiting seismic phases on Mars.

Author

Irving, Jessica C. E., Lekić, Vedran, Durán, Cecilia, Drilleau, Mélanie, Kim, Doyeon, Rivoldini, Attilio, Khan, Amir, Samuel, Henri, Antonangeli, Daniele, Banerdt, William Bruce, Beghein, Caroline, Bozdağ, Ebru, Ceylan, Savas, Charalambous, Constantinos, Clinton, John, Davis, Paul, Garcia, Raphaël, Giardini, Domenico, Horleston, Anna Catherine, and Quancheng Huang

Subjects
*MARS (Planet), *BULK modulus, *SEISMIC waves, *LONGITUDINAL waves, *CORE-mantle boundary
Abstract

We present the first observations of seismic waves propagating through the core of Mars. These observations, made using seismic data collected by the InSight geophysical mission, have allowed us to construct the first seismically constrained models for the elastic properties of Mars' core. We observe core-transiting seismic phase SKS from two farside seismic events detected on Mars and measure the travel times of SKS relative to mantle traversing body waves. SKS travels through the core as a compressional wave, providing information about bulk modulus and density. We perform probabilistic inversions using the core-sensitive relative travel times together with gross geophysical data and travel times from other, more proximal, seismic events to seek the equation of state parameters that best describe the liquid iron-alloy core. Our inversions provide constraints on the velocities in Mars' core and are used to develop the first seismically based estimates of its composition. We show that models informed by our SKS data favor a somewhat smaller (median core radius = 1,780 to 1,810 km) and denser (core density = 6.2 to 6.3 g/cm3) core compared to previous estimates, with a P-wave velocity of 4.9 to 5.0 km/s at the core-mantle boundary, with the composition and structure of the mantle as a dominant source of uncertainty. We infer from our models that Mars' core contains a median of 20 to 22 wt% light alloying elements when we consider sulfur, oxygen, carbon, and hydrogen. These data can be used to inform models of planetary accretion, composition, and evolution. [ABSTRACT FROM AUTHOR]

Published
2023
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22. The Far Side of Mars: Two Distant Marsquakes Detected by InSight

Author

Horleston, Anna C., primary, Clinton, John F., additional, Ceylan, Savas, additional, Giardini, Domenico, additional, Charalambous, Constantinos, additional, Irving, Jessica C. E., additional, Lognonné, Philippe, additional, Stähler, Simon C., additional, Zenhäusern, Géraldine, additional, Dahmen, Nikolaj L., additional, Duran, Cecilia, additional, Kawamura, Taichi, additional, Khan, Amir, additional, Kim, Doyeon, additional, Plasman, Matthieu, additional, Euchner, Fabian, additional, Beghein, Caroline, additional, Beucler, Éric, additional, Huang, Quancheng, additional, Knapmeyer, Martin, additional, Knapmeyer-Endrun, Brigitte, additional, Lekić, Vedran, additional, Li, Jiaqi, additional, Perrin, Clément, additional, Schimmel, Martin, additional, Schmerr, Nicholas C., additional, Stott, Alexander E., additional, Stutzmann, Eléonore, additional, Teanby, Nicholas A., additional, Xu, Zongbo, additional, Panning, Mark, additional, and Banerdt, William B., additional

Published
2022
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24. re-examination of ellipticity corrections for seismic phases.

Author

Russell, Stuart, Rudge, John F, Irving, Jessica C E, and Cottaar, Sanne

Subjects
SEISMIC waves, SEISMOLOGISTS, MARS (Planet)
Abstract

The Earth's ellipticity of figure has an effect on the traveltimes of seismic waves over teleseismic distances. Tables of ellipticity corrections and coefficients have been used by seismologists for several decades; however, due to the increasing variety and complexity of seismic phases in use, current tables of ellipticity coefficients are now outmoded and incomplete. We present a Python package, EllipticiPy, for the calculation of ellipticity corrections, which removes the dependence on pre-calculated coefficients at discrete source depths and epicentral distances. EllipticiPy also facilitates the calculation of ellipticity corrections on other planetary bodies. When applied to both Earth and Mars, the magnitudes of ellipticity corrections are of the order of single seconds and are significant for some seismic studies on Earth but remain negligible on Mars due to other greater sources of uncertainty. [ABSTRACT FROM AUTHOR]

Published
2022
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25. Seismic detection of a deep mantle discontinuity within Mars by InSight.

Author

Quancheng Huang, Schmerr, Nicholas C., King, Scott D., Kim, Doyeon, Rivoldini, Attilio, Plesa, Ana-Catalina, Samuel, Henri, Maguire, Ross R., Karakostas, Foivos, Lekić, Vedran, Charalambous, Constantinos, Collinet, Max, Myhill, Robert, Antonangeli, Daniele, Drilleau, Mèlanie, Bystricky, Misha, Bollinger, Caroline, Michaut, Chloè, Gudkova, Tamara, and Irving, Jessica C. E.

Subjects
MARS (Planet), SHEAR waves, IRON, PHASE transitions, OLIVINE
Abstract

Constraining the thermal and compositional state of the mantle is crucial for deciphering the formation and evolution of Mars. Mineral physics predicts that Mars’ deep mantle is demarcated by a seismic discontinuity arising from the pressureinduced phase transformation of the mineral olivine to its higher-pressure polymorphs, making the depth of this boundary sensitive to both mantle temperature and composition. Here, we report on the seismic detection of a midmantle discontinuity using the data collected by NASA’s InSight Mission to Mars that matches the expected depth and sharpness of the postolivine transition. In five teleseismic events, we observed triplicated P and S waves and constrained the depth of this discontinuity to be 1,006 ± 40 km by modeling the triplicated waveforms. From this depth range, we infer a mantle potential temperature of 1,605 ± 100 K, a result consistent with a crust that is 10 to 15 times more enriched in heat-producing elements than the underlying mantle. Our waveform fits to the data indicate a broad gradient across the boundary, implying that the Martian mantle is more enriched in iron compared to Earth. Through modeling of thermochemical evolution of Mars, we observe that only two out of the five proposed composition models are compatible with the observed boundary depth. Our geodynamic simulations suggest that the Martian mantle was relatively cold 4.5 Gyr ago (1,720 to 1,860 K) and are consistent with a present-day surface heat flow of 21 to 24 mW/m². [ABSTRACT FROM AUTHOR]

Published
2022
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27. Seismic detection of the martian core

Author

Stähler, Simon C., primary, Khan, Amir, additional, Banerdt, W. Bruce, additional, Lognonné, Philippe, additional, Giardini, Domenico, additional, Ceylan, Savas, additional, Drilleau, Mélanie, additional, Duran, A. Cecilia, additional, Garcia, Raphaël F., additional, Huang, Quancheng, additional, Kim, Doyeon, additional, Lekic, Vedran, additional, Samuel, Henri, additional, Schimmel, Martin, additional, Schmerr, Nicholas, additional, Sollberger, David, additional, Stutzmann, Éléonore, additional, Xu, Zongbo, additional, Antonangeli, Daniele, additional, Charalambous, Constantinos, additional, Davis, Paul M., additional, Irving, Jessica C. E., additional, Kawamura, Taichi, additional, Knapmeyer, Martin, additional, Maguire, Ross, additional, Marusiak, Angela G., additional, Panning, Mark P., additional, Perrin, Clément, additional, Plesa, Ana-Catalina, additional, Rivoldini, Attilio, additional, Schmelzbach, Cédric, additional, Zenhäusern, Géraldine, additional, Beucler, Éric, additional, Clinton, John, additional, Dahmen, Nikolaj, additional, van Driel, Martin, additional, Gudkova, Tamara, additional, Horleston, Anna, additional, Pike, W. Thomas, additional, Plasman, Matthieu, additional, and Smrekar, Suzanne E., additional

Published
2021
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31. The interior of Mars as seen by InSight (Invited)

Author

Staehler, Simon C., Khan, A., Knapmeyer‐Endrun, Brigitte, Panning, Mark P., Banerdt, William B., Lognonné, P., Giardini, Domenico, Antonangeli, D., Beucler, E., Bissig, F., Bozdag, E., Brinkmann, N., Ceylan, S., Charalambous, C., Clinton, John F., Compaire, Nicolas, Dahmen, N. L., Davis, P., van Driel, M., Drilleau, M., Garcia, Raphael F., Huang, Quancheng, Joshi, Rakshit, Gudkova, T., Irving, Jessica C. E., Johnson, C., Kawamura, T., Kim, Doyeon, Knapmeyer, Martin, Maguire, R., Lekic, Vedran, Margerin, L., Marusiak, A, McLennan, S M, Mittelholz, A., Michaut, Chloe, Plasman, M., Pan, L., Duran, C., Perrin, C., Pike, T., Plesa, Ana-Catalina, Pinot, Baptiste, Rivoldini, A., Scholz, J.-R., Schimmel, Martin, Schmerr, N., Stutzmann, Éléonore, Samuel, H., Smrekar, S., Spohn, Tilman, Tauzin, B., Tharimena, S., Widmer-Schnidrig, R, Wieczorek, M., Xu, Zongbo, Zenhäusern, Geraldine, Karakostas, F., and InSight, Science Team

Abstract

InSight is the first planetary mission dedicated to exploring the whole interior of a planet using geophysical methods, specifically seismology and geodesy. To this end, we observed seismic waves of distant marsquakes and inverted for interior models using differential travel times of phases reflected at the surface (PP, SS...) or the core mantle-boundary (ScS), as well as those converted at crustal interfaces. Compared to previous orbital observations1-3, the seismic data added decisive new insights with consequences for the formation of Mars: The global average crustal thickness of 24-75 km is at the low end of pre-mission estimates5. Together with the the thick lithosphere of 450-600 km5, this requires an enrichment of heat-producing elements in the crust by a factor of 13-20, compared to the primitive mantle. The iron-rich liquid core is 1790-1870 km in radius6, which rules out the existence of an insulating bridgmanite-dominated lower mantle on Mars. The large, and therefore low-density core needs a high amount of light elements. Given the geochemical boundary conditions, Sulfur alone cannot explain the estimated density of ~6 g/cm3 and volatile elements, such as oxygen, carbon or hydrogen are needed in significant amounts. This observation is difficult to reconcile with classical models of late formation from the same material as Earth. We also give an overview of open questions after three years of InSight operation on the surface of Mars, such as the potential existence of an inner core or compositional layers above the CMB

Published
2021

32. Potential Pitfalls in the Analysis and Structural Interpretation of Seismic Data from the Mars InSight Mission

Author

Kim, Doyeon, Davis, Paul, Lekic, Ved, Maguire, Ross, Compaire, Nicolas, Schimmel, Martin, Stutzmann, Eleonore, Irving, Jessica C. E., Lognonne, Philippe, Scholz, John-Robert, Clinton, John, Zenhaeusern, Geraldine, Dahmen, Nikolaj, Deng, Sizhuang, Levander, Alan, Panning, Mark P., Garcia, Raphael F., Giardini, Domenico, Hurst, Ken, Knapmeyer-Endrun, Brigitte, Nimmo, Francis, Pike, W. Tom, Pou, Laurent, Schmerr, Nicholas, Staehler, Simon C., Tauzin, Benoit, Widmer-Schnidrig, Rudolf, Banerdt, William B., Kim, Doyeon, Davis, Paul, Lekic, Ved, Maguire, Ross, Compaire, Nicolas, Schimmel, Martin, Stutzmann, Eleonore, Irving, Jessica C. E., Lognonne, Philippe, Scholz, John-Robert, Clinton, John, Zenhaeusern, Geraldine, Dahmen, Nikolaj, Deng, Sizhuang, Levander, Alan, Panning, Mark P., Garcia, Raphael F., Giardini, Domenico, Hurst, Ken, Knapmeyer-Endrun, Brigitte, Nimmo, Francis, Pike, W. Tom, Pou, Laurent, Schmerr, Nicholas, Staehler, Simon C., Tauzin, Benoit, Widmer-Schnidrig, Rudolf, and Banerdt, William B.

Abstract

The Seismic Experiment for Interior Structure (SEIS) of the InSight mission to Mars has been providing direct information on Martian interior structure and dynamics of that planet since it landed. Compared with seismic recordings on the Earth, ground-motion measurements acquired by SEIS on Mars are not only made under dramatically different ambient noise conditions, but also include idiosyncratic signals that arise from coupling between different InSight sensors and spacecraft components. This work is to synthesize what is known about these signal types, illustrate how they can manifest in waveforms and noise correlations, and present pitfalls in structural interpretations based on standard seismic analysis methods. We show that glitches (a type of prominent transient signal) can produce artifacts in ambient noise correlations. Sustained signals that vary in frequency, such as lander modes that are affected by variations in temperature and wind conditions over the course of the Martian sol, can also contaminate ambient noise results. Therefore, both types of signals have the potential to bias interpretation in terms of subsurface layering. We illustrate that signal processing in the presence of identified nonseismic signals must be informed by an understanding of the underlying physical processes in order for high-fidelity waveforms of ground motion to be extracted. Whereas the origins of the most idiosyncratic signals are well understood, the 2.4 Hz resonance remains debated, and the literature does not contain an explanation of its fine spectral structure. Even though the selection of idiosyncratic signal types discussed in this article may not be exhaustive, we provide guidance on the best practices for enhancing the robustness of structural interpretations.

Published
2021

33. A MERMAID Miscellany: Seismoacoustic Signals beyond the P Wave

Author

Simon, Joel D., Simons, Frederik J., Irving, Jessica C. E., Simon, Joel D., Simons, Frederik J., and Irving, Jessica C. E.

Abstract

Mobile Earthquake Recorder in Marine Areas by Independent Divers (MERMAID) is a passively drifting oceanic diving float that transmits acoustic pressure records from global earthquakes within hours or days of their rupture. The onboard algorithm used for the detection and identification of signals from the hydrophone prioritizes the recovery of similar to 1 Hz teleseismic P waves, which are useful for seismic imaging of Earth's mantle. Two years into a mission that launched 50 MERMAIDs to map 3D mantle wavespeed anomalies with high resolution under the Pacific in French Polynesia, it is clear that the data returned contain much information beyond the first-arriving seismic P phases. These include acoustic conversions from S waves, surface waves, Twaves, and inner- and outer-core phases, generated by earthquakes heard across the globe-and sounds from otherwise unidentified events occurring in remote and uninstrumented parts of the world's oceans. Our growing database of automatically accumulating similar to 240 s long-triggered segments contains a treasure trove for geophysicists interested in seismology beyond P-wave tomography. Furthermore, equipped with two-way communication capabilities, MERMAID can entertain requests to deliver data from its 1 yr buffer. In this article, we highlight the data classes and categories in MERMAID'S "extended-utility" catalog.

Published
2021
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34. Potential Pitfalls in the Analysis and Structural Interpretation of Seismic Data from the Mars InSight Mission

Author

German Centre for Air and Space Travel, David and Lucile Packard Foundation, California Institute of Technology, Ministerio de Ciencia, Innovación y Universidades (España), Generalitat de Catalunya, European Commission, Agence Nationale de la Recherche (France), Schimmel, Martin [0000-0003-2601-4462], Kim, Doyeon, Davis, Paul, Lekic, Vedran, Maguire, Ross, Compaire, Nicolas, Schimmel, Martin, Stutzmann, E., Irving, Jessica C. E., Lognonné, P., Scholz, J. R., Clinton, John F., Zenhäusern, G., Deng, Sizhuang, Levander, A., Panning, Mark P., Garcia, Raphael F., Giardini, Domenico, Hurst, K., Knapmeyer‐Endrun, Brigitte, Nimmo, F., Pike, William T., Pou, Laurent, Schmerr, N., Stahler, S. C., Tauzin, Benoit, Widmer‐Schnidrig, Rudolf, Banerdt, William B., German Centre for Air and Space Travel, David and Lucile Packard Foundation, California Institute of Technology, Ministerio de Ciencia, Innovación y Universidades (España), Generalitat de Catalunya, European Commission, Agence Nationale de la Recherche (France), Schimmel, Martin [0000-0003-2601-4462], Kim, Doyeon, Davis, Paul, Lekic, Vedran, Maguire, Ross, Compaire, Nicolas, Schimmel, Martin, Stutzmann, E., Irving, Jessica C. E., Lognonné, P., Scholz, J. R., Clinton, John F., Zenhäusern, G., Deng, Sizhuang, Levander, A., Panning, Mark P., Garcia, Raphael F., Giardini, Domenico, Hurst, K., Knapmeyer‐Endrun, Brigitte, Nimmo, F., Pike, William T., Pou, Laurent, Schmerr, N., Stahler, S. C., Tauzin, Benoit, Widmer‐Schnidrig, Rudolf, and Banerdt, William B.

Abstract

The Seismic Experiment for Interior Structure (SEIS) of the InSight mission to Mars has been providing direct information on Martian interior structure and dynamics of that planet since it landed. Compared with seismic recordings on the Earth, ground‐motion measurements acquired by SEIS on Mars are not only made under dramatically different ambient noise conditions, but also include idiosyncratic signals that arise from coupling between different InSight sensors and spacecraft components. This work is to synthesize what is known about these signal types, illustrate how they can manifest in waveforms and noise correlations, and present pitfalls in structural interpretations based on standard seismic analysis methods. We show that glitches (a type of prominent transient signal) can produce artifacts in ambient noise correlations. Sustained signals that vary in frequency, such as lander modes that are affected by variations in temperature and wind conditions over the course of the Martian sol, can also contaminate ambient noise results. Therefore, both types of signals have the potential to bias interpretation in terms of subsurface layering. We illustrate that signal processing in the presence of identified nonseismic signals must be informed by an understanding of the underlying physical processes in order for high‐fidelity waveforms of ground motion to be extracted. Whereas the origins of the most idiosyncratic signals are well understood, the 2.4 Hz resonance remains debated, and the literature does not contain an explanation of its fine spectral structure. Even though the selection of idiosyncratic signal types discussed in this article may not be exhaustive, we provide guidance on the best practices for enhancing the robustness of structural interpretations.

Published
2021

35. Seismic detection of the martian core

Author

NASA Jet Propulsion Laboratory, European Commission, Agence Nationale de la Recherche (France), Belgian Science Policy Office, European Space Agency, Ministerio de Ciencia, Innovación y Universidades (España), UK Space Agency, Stahler, S. C., Khan, A., Banerdt, W. B., Lognonné, P., Giardini, Domenico, Ceylan, S., Drilleau, M., Duran, A. C., Garcia, R. F., Huang, Q. C., Kim, D., Lekic, Vedran, Samuel, H., Schimmel, Martin, Schmerr, N., Sollberger, D., Stutzmann, E., Xu, Z. D., Antonangeli, D., Charalambous, C., Davis, P. M., Irving, Jessica C. E., Kawamura, T., Knapmeyer, M., Maguire, R., Marusiak, A. G., Panning, M.P., Perrin , C., Plesa, A. C., Rivoldini, A., Schmelzbach, C., Zenhausern, G., Beucler, E., Clinton, John F., Dahmen, N., van Driel, M., Gudkova, T., Horleston, A., Pike, William T., Plasman, M., Smrekar, S. E., NASA Jet Propulsion Laboratory, European Commission, Agence Nationale de la Recherche (France), Belgian Science Policy Office, European Space Agency, Ministerio de Ciencia, Innovación y Universidades (España), UK Space Agency, Stahler, S. C., Khan, A., Banerdt, W. B., Lognonné, P., Giardini, Domenico, Ceylan, S., Drilleau, M., Duran, A. C., Garcia, R. F., Huang, Q. C., Kim, D., Lekic, Vedran, Samuel, H., Schimmel, Martin, Schmerr, N., Sollberger, D., Stutzmann, E., Xu, Z. D., Antonangeli, D., Charalambous, C., Davis, P. M., Irving, Jessica C. E., Kawamura, T., Knapmeyer, M., Maguire, R., Marusiak, A. G., Panning, M.P., Perrin , C., Plesa, A. C., Rivoldini, A., Schmelzbach, C., Zenhausern, G., Beucler, E., Clinton, John F., Dahmen, N., van Driel, M., Gudkova, T., Horleston, A., Pike, William T., Plasman, M., and Smrekar, S. E.

Abstract

Clues to a planet's geologic history are contained in its interior structure, particularly its core. We detected reflections of seismic waves from the core-mantle boundary of Mars using InSight seismic data and inverted these together with geodetic data to constrain the radius of the liquid metal core to 1830 +/- 40 kilometers. The large core implies a martian mantle mineralogically similar to the terrestrial upper mantle and transition zone but differing from Earth by not having a bridgmanite-dominated lower mantle. We inferred a mean core density of 5.7 to 6.3 grams per cubic centimeter, which requires a substantial complement of light elements dissolved in the iron-nickel core. The seismic core shadow as seen from InSight's location covers half the surface of Mars, including the majority of potentially active regions-e.g., Tharsis-possibly limiting the number of detectable marsquakes.

Published
2021

36. Global quieting of high-frequency seismic noise due to COVID-19 pandemic lockdown measures

Author

Lecocq, Thomas, Hicks, Stephen P., Van Noten, Koen, van Wijk, Kasper, Koelemeijer, Paula, De Plaen, Raphael S. M., Massin, Frederick, Hillers, Gregor, Anthony, Robert E., Apoloner, Maria-Theresia, Arroyo-Solorzano, Mario, Assink, Jelle D., Bueyuekakpinar, Pinar, Cannata, Andrea, Cannavo, Flavio, Carrasco, Sebastian, Caudron, Corentin, Chaves, Esteban J., Cornwell, David G., Craig, David, den Ouden, Olivier F. C., Diaz, Jordi, Donner, Stefanie, Evangelidis, Christos P., Evers, Laslo, Fauville, Benoit, Fernandez, Gonzalo A., Giannopoulos, Dimitrios, Gibbons, Steven J., Girona, Tarsilo, Grecu, Bogdan, Grunberg, Marc, Hetenyi, Gyorgy, Horleston, Anna, Inza, Adolfo, Irving, Jessica C. E., Jamalreyhani, Mohammadreza, Kafka, Alan, Koymans, Mathijs R., Labedz, Celeste R., Larose, Eric, Lindsey, Nathaniel J., McKinnon, Mika, Megies, Tobias, Miller, Meghan S., Minarik, William, Moresi, Louis, Marquez-Ramirez, Victor H., Mollhoff, Martin, Nesbitt, Ian M., Niyogi, Shankho, Ojeda, Javier, Oth, Adrien, Proud, Simon, Pulli, Jay, Retailleau, Lise, Rintamaki, Annukka E., Satriano, Claudio, Savage, Martha K., Shani-Kadmiel, Shahar, Sleeman, Reinoud, Sokos, Efthimios, Stammler, Klaus, Stott, Alexander E., Subedi, Shiba, Sorensen, Mathilde B., Taira, Taka'aki, Tapia, Mar, Turhan, Fatih, van der Pluijm, Ben, Vanstone, Mark, Vergne, Jerome, Vuorinen, Tommi A. T., Warren, Tristram, Wassermann, Joachim, Xiao, Han, Lecocq, Thomas, Hicks, Stephen P., Van Noten, Koen, van Wijk, Kasper, Koelemeijer, Paula, De Plaen, Raphael S. M., Massin, Frederick, Hillers, Gregor, Anthony, Robert E., Apoloner, Maria-Theresia, Arroyo-Solorzano, Mario, Assink, Jelle D., Bueyuekakpinar, Pinar, Cannata, Andrea, Cannavo, Flavio, Carrasco, Sebastian, Caudron, Corentin, Chaves, Esteban J., Cornwell, David G., Craig, David, den Ouden, Olivier F. C., Diaz, Jordi, Donner, Stefanie, Evangelidis, Christos P., Evers, Laslo, Fauville, Benoit, Fernandez, Gonzalo A., Giannopoulos, Dimitrios, Gibbons, Steven J., Girona, Tarsilo, Grecu, Bogdan, Grunberg, Marc, Hetenyi, Gyorgy, Horleston, Anna, Inza, Adolfo, Irving, Jessica C. E., Jamalreyhani, Mohammadreza, Kafka, Alan, Koymans, Mathijs R., Labedz, Celeste R., Larose, Eric, Lindsey, Nathaniel J., McKinnon, Mika, Megies, Tobias, Miller, Meghan S., Minarik, William, Moresi, Louis, Marquez-Ramirez, Victor H., Mollhoff, Martin, Nesbitt, Ian M., Niyogi, Shankho, Ojeda, Javier, Oth, Adrien, Proud, Simon, Pulli, Jay, Retailleau, Lise, Rintamaki, Annukka E., Satriano, Claudio, Savage, Martha K., Shani-Kadmiel, Shahar, Sleeman, Reinoud, Sokos, Efthimios, Stammler, Klaus, Stott, Alexander E., Subedi, Shiba, Sorensen, Mathilde B., Taira, Taka'aki, Tapia, Mar, Turhan, Fatih, van der Pluijm, Ben, Vanstone, Mark, Vergne, Jerome, Vuorinen, Tommi A. T., Warren, Tristram, Wassermann, Joachim, and Xiao, Han

Abstract

Human activity causes vibrations that propagate into the ground as high-frequency seismic waves. Measures to mitigate the coronavirus disease 2019 (COVID-19) pandemic caused widespread changes in human activity, leading to a months-long reduction in seismic noise of up to 50%. The 2020 seismic noise quiet period is the longest and most prominent global anthropogenic seismic noise reduction on record. Although the reduction is strongest at surface seismometers in populated areas, this seismic quiescence extends for many kilometers radially and hundreds of meters in depth. This quiet period provides an opportunity to detect subtle signals from subsurface seismic sources that would have been concealed in noisier times and to benchmark sources of anthropogenic noise. A strong correlation between seismic noise and independent measurements of human mobility suggests that seismology provides an absolute, real-time estimate of human activities.

Published
2020

38. Global quieting of high-frequency seismic noise due to COVID-19 pandemic lockdown measures

Author

Lecocq, Thomas, primary, Hicks, Stephen P., additional, Van Noten, Koen, additional, van Wijk, Kasper, additional, Koelemeijer, Paula, additional, De Plaen, Raphael S. M., additional, Massin, Frédérick, additional, Hillers, Gregor, additional, Anthony, Robert E., additional, Apoloner, Maria-Theresia, additional, Arroyo-Solórzano, Mario, additional, Assink, Jelle D., additional, Büyükakpınar, Pinar, additional, Cannata, Andrea, additional, Cannavo, Flavio, additional, Carrasco, Sebastian, additional, Caudron, Corentin, additional, Chaves, Esteban J., additional, Cornwell, David G., additional, Craig, David, additional, den Ouden, Olivier F. C., additional, Diaz, Jordi, additional, Donner, Stefanie, additional, Evangelidis, Christos P., additional, Evers, Läslo, additional, Fauville, Benoit, additional, Fernandez, Gonzalo A., additional, Giannopoulos, Dimitrios, additional, Gibbons, Steven J., additional, Girona, Társilo, additional, Grecu, Bogdan, additional, Grunberg, Marc, additional, Hetényi, György, additional, Horleston, Anna, additional, Inza, Adolfo, additional, Irving, Jessica C. E., additional, Jamalreyhani, Mohammadreza, additional, Kafka, Alan, additional, Koymans, Mathijs R., additional, Labedz, Celeste R., additional, Larose, Eric, additional, Lindsey, Nathaniel J., additional, McKinnon, Mika, additional, Megies, Tobias, additional, Miller, Meghan S., additional, Minarik, William, additional, Moresi, Louis, additional, Márquez-Ramírez, Víctor H., additional, Möllhoff, Martin, additional, Nesbitt, Ian M., additional, Niyogi, Shankho, additional, Ojeda, Javier, additional, Oth, Adrien, additional, Proud, Simon, additional, Pulli, Jay, additional, Retailleau, Lise, additional, Rintamäki, Annukka E., additional, Satriano, Claudio, additional, Savage, Martha K., additional, Shani-Kadmiel, Shahar, additional, Sleeman, Reinoud, additional, Sokos, Efthimios, additional, Stammler, Klaus, additional, Stott, Alexander E., additional, Subedi, Shiba, additional, Sørensen, Mathilde B., additional, Taira, Taka'aki, additional, Tapia, Mar, additional, Turhan, Fatih, additional, van der Pluijm, Ben, additional, Vanstone, Mark, additional, Vergne, Jerome, additional, Vuorinen, Tommi A. T., additional, Warren, Tristram, additional, Wassermann, Joachim, additional, and Xiao, Han, additional

Published
2020
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41. Potential Pitfalls in the Analysis and Structural Interpretation of Seismic Data from the Mars InSight Mission.

Author

Doyeon Kim, Davis, Paul, Lekić, Ved, Maguire, Ross, Compaire, Nicolas, Schimmel, Martin, Stutzmann, Eleonore, Irving, Jessica C. E., Lognonné, Philippe, Scholz, John-Robert, Clinton, John, Zenhäusern, Géraldine, Dahmen, Nikolaj, Sizhuang Deng, Levander, Alan, Panning, Mark P., Garcia, Raphaël F., Giardini, Domenico, Hurst, Ken, and Knapmeyer-Endrun, Brigitte

Abstract

The Seismic Experiment for Interior Structure (SEIS) of the InSight mission to Mars has been providing direct information on Martian interior structure and dynamics of that planet since it landed. Compared with seismic recordings on the Earth, ground-motion measurements acquired by SEIS on Mars are not only made under dramatically different ambient noise conditions, but also include idiosyncratic signals that arise from coupling between different InSight sensors and spacecraft components. This work is to synthesize what is known about these signal types, illustrate how they can manifest in waveforms and noise correlations, and present pitfalls in structural interpretations based on standard seismic analysis methods. We show that glitches (a type of prominent transient signal) can produce artifacts in ambient noise correlations. Sustained signals that vary in frequency, such as lander modes that are affected by variations in temperature and wind conditions over the course of the Martian sol, can also contaminate ambient noise results. Therefore, both types of signals have the potential to bias interpretation in terms of subsurface layering. We illustrate that signal processing in the presence of identified nonseismic signals must be informed by an understanding of the underlying physical processes in order for high-fidelity waveforms of ground motion to be extracted. Whereas the origins of the most idiosyncratic signals are well understood, the 2.4 Hz resonance remains debated, and the literature does not contain an explanation of its fine spectral structure. Even though the selection of idiosyncratic signal types discussed in this article may not be exhaustive, we provide guidance on the best practices for enhancing the robustness of structural interpretations. [ABSTRACT FROM AUTHOR]

Published
2021
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42. Seismically determined elastic parameters for Earth’s outer core

Author

Irving, Jessica C. E., Cottaar, Sanne, Lekić, Vedran, Cottaar, Sanne [0000-0003-0493-6570], and Apollo - University of Cambridge Repository

Subjects
Convection, Multidisciplinary, 010504 meteorology & atmospheric sciences, Velocity gradient, SciAdv r-articles, Mechanics, sub-02, 0404 Geophysics, 010502 geochemistry & geophysics, 01 natural sciences, Mantle (geology), Outer core, Magnetic field, law.invention, Physics::Geophysics, Condensed Matter::Materials Science, Geophysics, Normal mode, law, Compressibility, Preliminary reference Earth model, Research Articles, Geology, Research Article, 0105 earth and related environmental sciences
Abstract

Seismic properties and equation-of-state parameters of the liquid iron alloy in the outer core are inferred from normal mode data., Turbulent convection of the liquid iron alloy outer core generates Earth’s magnetic field and supplies heat to the mantle. The exact composition of the iron alloy is fundamentally linked to the processes powering the convection and can be constrained by its seismic properties. Discrepancies between seismic models determined using body waves and normal modes show that these properties are not yet fully agreed upon. In addition, technical challenges in experimentally measuring the equation-of-state (EoS) parameters of liquid iron alloys at high pressures and temperatures further complicate compositional inferences. We directly infer EoS parameters describing Earth’s outer core from normal mode center frequency observations and present the resulting Elastic Parameters of the Outer Core (EPOC) seismic model. Unlike alternative seismic models, ours requires only three parameters and guarantees physically realistic behavior with increasing pressure for a well-mixed homogeneous material along an isentrope, consistent with the outer core’s condition. We show that EPOC predicts available normal mode frequencies better than the Preliminary Reference Earth Model (PREM) while also being more consistent with body wave–derived models, eliminating a long-standing discrepancy. The velocity at the top of the outer core is lower, and increases with depth more steeply, in EPOC than in PREM, while the density in EPOC is higher than that in PREM across the outer core. The steeper profiles and higher density imply that the outer core comprises a lighter but more compressible alloy than that inferred for PREM. Furthermore, EPOC’s steeper velocity gradient explains differential SmKS body wave travel times better than previous one-dimensional global models, without requiring an anomalously slow ~90- to 450-km-thick layer at the top of the outer core.

Published
2018

45. Array‐Based Iterative Measurements of SmKS Travel Times and Their Constraints on Outermost Core Structure.

Author

Wu, Wenbo and Irving, Jessica C. E.

Subjects
*EARTH'S core, *CONVECTION (Meteorology), *P-waves (Seismology), *SEISMIC arrays, *SUBDUCTION zones, *TRAVEL time (Traffic engineering)
Abstract

Vigorous convection in Earth's outer core led to the suggestion that it is chemically homogeneous. However, there is increasing seismic evidence for structural complexities close to the outer core's upper and lower boundaries. Both body waves and normal mode data have been used to estimate a P wave velocity, Vp, at the top of the outer core (the E′ layer), which is lower than that in the Preliminary Reference Earth Model. However, these low Vp models do not agree on the form of this velocity anomaly. One reason for this is the difficulty in retrieving and measuring SmKS arrival times. To address this issue, we propose a novel approach using data from seismic arrays to iteratively measure SmKS‐ SKKS differential travel times. This approach extracts individual SmKS signal from mixed waveforms of the SmKS series, allowing us to reliably measure differential travel times. We successfully use this method to measure SmKS time delays from earthquakes in the Fiji‐Tonga and Vanuatu subduction zones. SmKS time delays are measured by waveform cross correlation between SmKS and SKKS, and the cross‐correlation coefficient allows us to access measurement quality. We also apply this iterative scheme to synthetic SmKS seismograms to investigate the 3‐D mantle structure's effects. The mantle structure corrections are not negligible for our data, and neglecting them could bias the Vp estimation of uppermost outer core. After mantle structure corrections, we can still see substantial time delays of S3KS, S4KS, and S5KS, supporting a low Vp at the top of Earth's outer core. Key Points: We develop an array‐based iterative method to measure SmKS‐ SKKS (m=3–5) differential travel timesThree‐dimensional mantle structure effects must be considered in studies of SmKS differential travel timesOur measurements support a low Vp at the top of outer core [ABSTRACT FROM AUTHOR]

Published
2020
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46. Array‐Based Iterative Measurements of SmKSTravel Times and Their Constraints on Outermost Core Structure

Author

Wu, Wenbo and Irving, Jessica C. E.

Abstract

Vigorous convection in Earth's outer core led to the suggestion that it is chemically homogeneous. However, there is increasing seismic evidence for structural complexities close to the outer core's upper and lower boundaries. Both body waves and normal mode data have been used to estimate a Pwave velocity, Vp, at the top of the outer core (the E′layer), which is lower than that in the Preliminary Reference Earth Model. However, these low Vpmodels do not agree on the form of this velocity anomaly. One reason for this is the difficulty in retrieving and measuring SmKSarrival times. To address this issue, we propose a novel approach using data from seismic arrays to iteratively measure SmKS‐ SKKSdifferential travel times. This approach extracts individual SmKSsignal from mixed waveforms of the SmKSseries, allowing us to reliably measure differential travel times. We successfully use this method to measure SmKStime delays from earthquakes in the Fiji‐Tonga and Vanuatu subduction zones. SmKStime delays are measured by waveform cross correlation between SmKSand SKKS, and the cross‐correlation coefficient allows us to access measurement quality. We also apply this iterative scheme to synthetic SmKSseismograms to investigate the 3‐D mantle structure's effects. The mantle structure corrections are not negligible for our data, and neglecting them could bias the Vpestimation of uppermost outer core. After mantle structure corrections, we can still see substantial time delays of S3KS, S4KS, and S5KS, supporting a low Vpat the top of Earth's outer core. We develop an array‐based iterative method to measure SmKS‐ SKKS( m=3–5) differential travel timesThree‐dimensional mantle structure effects must be considered in studies of SmKSdifferential travel timesOur measurements support a low Vpat the top of outer core

Published
2020
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47. Global quieting of high-frequency seismic noise due to COVID-19 pandemic lockdown measures

Author

Han Xiao, Ben A. van der Pluijm, Simon Richard Proud, Adolfo Inza, Stephen Hicks, T. Megies, Alexander E. Stott, William G. Minarik, Efthimios Sokos, Mika McKinnon, Kasper van Wijk, Anna Horleston, Victor H. Márquez-Ramírez, Läslo Evers, Bogdan Grecu, Esteban J. Chaves, Joachim Wassermann, Claudio Satriano, Christos Evangelidis, Paula Koelemeijer, David Craig, Frédérick Massin, Sebastián Carrasco, György Hetényi, Mario Arroyo-Solórzano, Eric Larose, Jay J. Pulli, Társilo Girona, Lise Retailleau, Javier Ojeda, Olivier F. C. den Ouden, Alan L. Kafka, Gonzalo A. Fernandez, Marc Grunberg, Tommi Vuorinen, Robert E. Anthony, Steven J. Gibbons, Stefanie Donner, Martin Möllhoff, Nathaniel J. Lindsey, Jordi Diaz, C. R. Labedz, Meghan S. Miller, Taka'aki Taira, Dave Cornwell, Mathijs Koymans, Corentin Caudron, Klaus Stammler, Andrea Cannata, Flavio Cannavò, Reinoud Sleeman, Mark Vanstone, Shiba Subedi, Raphael S. M. De Plaen, Shankho Niyogi, Koen Van Noten, Shahar Shani-Kadmiel, Jelle Assink, Tristram Warren, Jessica C. E. Irving, Ian M. Nesbitt, Dimitrios Giannopoulos, Martha K. Savage, Mohammadreza Jamalreyhani, Louis Moresi, Maria-Theresia Apoloner, Gregor Hillers, Jérôme Vergne, Benoit Fauville, Fatih Turhan, Annukka E. Rintamäki, Pınar Büyükakpınar, Adrien Oth, Mathilde B. Sørensen, Mar Tapia, Thomas Lecocq, Royal Society (UK), German Research Centre for Geosciences, Boğaziçi Üniversity, Netherlands Organization for Scientific Research, Air Force Office of Scientific Research (US), National Science Foundation (US), Consejo Nacional de Ciencia y Tecnología (México), Universidad Nacional Autónoma de México, Agencia Nacional de Investigación y Desarrollo (Chile), Natural Environment Research Council (UK), University of California, Commonwealth Scientific and Industrial Research Organisation (Australia), Belgian Science Policy Office, Fonds National de la Recherche Luxembourg, Lecocq, Thomas, Hicks, Stephen, Noten, Koen Van, Wijk, Kasper van, Plaen, Raphael de, Massin, Frédérick, Hillers, Gregor, Apoloner, Maria-Theresia, Arroyo-Solórzano, Mario, Assink, Jelle, Büyükakpınar, Pinar, Cannata, Andrea, Cannavó, Flavio, Carrasco, Sebastián, Caudron, Corentin, Chaves, Esteban, Cornwell, David G., Craig, David, Diaz, J., Donner, Stefanie, Evangelidis, Christos, Evers, Läslo, Fernández, Gonzalo A., Giannopoulos, Dimitrios, Gibbons, Steven J., Girona, Társilo, Grecu, Bogdan, Grunberg, Marc, Hetényi, Gyorgy, Horleston, Anna, Inza, Adolfo, Irving, Jessica C. E., Jamalreyhani, Mohammadreza, Kafka, Alan, Labedz, Celeste, Lindsey, Nathaniel, McKinno, Mika, Megies, Tobias, Miller, Meghan, Minarik, William, Moresi, Louis, Márquez-Ramirez, V. H., Möllhoff, Martin, Nesbitt, Ian M., Niyogi, Shankho, Ojeda, Javier, Oth, Adrien, Proud, Simon, Retailleau, Lise, Satriano, Claudio, Savage, Martha, Shani-Kadmiel, Shahar, Sleeman,Reinoud, Sokos, Efthimios, Stott, Alexander, Subedi, Shiba, Sørensen, Mathilde, Taira, Taka'aki, Turhan, Fatih, Pluijm, Ben van der, Vergne, Jérôme, Vuorinen, Tommi A. T., Warren, Tristram, Wassermann, Joachim, Xiao, Han, Lecocq, Thomas [0000-0002-4988-6477], Hicks, Stephen [0000-0002-7476-3284], Noten, Koen Van [0000-0001-8933-4426], Wijk, Kasper van [0000-0003-4994-8030], Plaen, Raphael de [0000-0003-3477-2001], Massin, Frédérick [0000-0002-7532-5139], Hillers, Gregor [0000-0003-2341-1892], Apoloner, Maria-Theresia [0000-0002-4006-1284], Arroyo-Solórzano, Mario [0000-0002-1653-2680], Assink, Jelle [0000-0002-4990-6845], Büyükakpınar, Pinar [0000-0001-8461-674X], Cannata, Andrea [0000-0002-0028-5822], Cannavó, Flavio [0000-0001-7550-8579], Carrasco, Sebastián [0000-0002-6207-8757], Caudron, Corentin [0000-0002-3748-0007], Chaves, Esteban [0000-0002-5724-1513], Cornwell, David G. [0000-0002-9843-7811], Craig, David [0000-0001-9414-1725], Diaz, J. [0000-0003-1801-0541], Donner, Stefanie [0000-0001-7351-8079], Evangelidis, Christos [0000-0001-8733-8984], Evers, Läslo [0000-0003-2825-6211], Fernández, Gonzalo A. [0000-0001-8284-9566], Giannopoulos, Dimitrios [0000-0002-8314-0759], Gibbons, Steven J. [0000-0002-7822-0244], Girona, Társilo [0000-0001-6422-0422], Grecu, Bogdan [0000-0002-7662-996X], Grunberg, Marc [0000-0002-1307-7790], Hetényi, Gyorgy [0000-0001-9036-4761], Horleston, Anna [0000-0002-6748-6522], Inza, Adolfo [0000-0001-5381-9042], Irving, Jessica C. E. [0000-0002-0866-8246], Jamalreyhani, Mohammadreza [0000-0003-4181-7175], Kafka, Alan [0000-0001-6643-1602], Labedz, Celeste [0000-0001-7339-2170], Lindsey, Nathaniel [0000-0001-9522-6683], McKinno, Mika [0000-0002-9274-0377], Megies, Tobias [0000-0002-5033-9921], Miller, Meghan [0000-0001-5494-2296], Minarik, William [0000-0001-5509-5543], Moresi, Louis [0000-0003-3685-174X], Márquez-Ramirez, V. H. [0000-0003-1494-2229], Möllhoff, Martin [0000-0003-1848-1554], Nesbitt, Ian M. [0000-0001-5828-6070], Niyogi, Shankho [0000-0002-8362-4569], Ojeda, Javier [0000-0002-7188-8356], Oth, Adrien [0000-0003-4859-6504], Proud, Simon [0000-0003-3880-6774], Retailleau, Lise [0000-0002-0711-4540], Satriano, Claudio [0000-0002-3039-2530], Savage, Martha [0000-0002-2080-0676], Shani-Kadmiel, Shahar [0000-0003-2215-6164], Sleeman,Reinoud [0000-0002-1928-5056], Sokos, Efthimios [0000-0002-7742-7251], Stott, Alexander [0000-0001-6121-705X], Subedi, Shiba [0000-0002-7009-7333], Sørensen, Mathilde [0000-0002-8589-7480], Taira, Taka'aki [0000-0002-6170-797X], Turhan, Fatih [0000-0003-4612-7421], Pluijm, Ben van der [0000-0001-7737-2791], Vergne, Jérôme [0000-0003-1731-9360], Vuorinen, Tommi A. T. [0000-0002-8186-012X], Warren, Tristram [0000-0003-3877-0046], Wassermann, Joachim [0000-0002-4088-1792], and Xiao, Han [0000-0001-8727-8053]

Subjects
Seismometer, 2019-20 coronavirus outbreak, 010504 meteorology & atmospheric sciences, Coronavirus disease 2019 (COVID-19), General Science & Technology, Pneumonia, Viral, Seismic noise, 010502 geochemistry & geophysics, 01 natural sciences, Seismic wave, Activities of Daily Living, Humans, Pandemics, 0105 earth and related environmental sciences, Multidisciplinary, COVID-19, Covid19, Noise, Quiet period, Quarantine, Séismologie, Coronavirus Infections, Geology, Seismology
Abstract

Human activity causes vibrations that propagate into the ground as high-frequency seismic waves. Measures to mitigate the COVID-19 pandemic caused widespread changes in human activity, leading to a months-long reduction in seismic noise of up to 50%. The 2020 seismic noise quiet period is the longest and most prominent global anthropogenic seismic noise reduction on record. While the reduction is strongest at surface seismometers in populated areas, this seismic quiescence extends for many kilometers radially and hundreds of meters in depth. This provides an opportunity to detect subtle signals from subsurface seismic sources that would have been concealed in noisier times and to benchmark sources of anthropogenic noise. A strong correlation between seismic noise and independent measurements of human mobility suggests that seismology provides an absolute, real-time estimate of population dynamics., P.K. was funded by a Royal Society University Research Fellowship (URF\R1\180377). P.B. and M.J. acknowledge support from the International Training Course “Seismology and Seismic Hazard Assessment” funded by the GeoForschungsZentrum Potsdam (GFZ) and the German Federal Foreign Office through the German Humanitarian Assistance program (grant S08-60 321.50 ALL 03/19). P.B also acknowledges financial support from the Boğaziçi University Research Fund (BAP 15683). O.F.C.d.O acknowledges funding from a Young Investigator Grant from the Human Frontier Science Program (HFSP - project number RGY0072/2017). C.P.E. and E.S. acknowledge funding from the HELPOS Project “Hellenic Plate Observing System” (MIS 5002697). L.E. and S.S.-K. acknowledge funding from a VIDI project from the Dutch Research Council (NWO project number 864.14.005). G.A.F. acknowledges contributions from the Observatorio San Calixto, which is supported by the Air Force Technical Application Center (AFTAC). C.R.L. acknowledge funding from the NSF Graduate Research Fellowship Program (grant No. DGE‐1745301). V.-H.M. and R.D.P. acknowledge support from grant CONACYT-299766. R.D.P. acknowledges support from the UNAM-DGAPA postdoctoral scholarship. J.O. acknowledges support from the Agencia Nacional de Investigación y Desarrollo (Scholarship ANID-PFCHA / Doctorado Nacional / 2020-21200903). S.P. acknowledges financial support from the Natural Environment Research Council (NE/R013144/1). A.E.R. acknowledges support from the K.H. Renlund foundation. M.K.S. acknowledges the New Zealand Earthquake Commission (EQC Project No 20796). H.X. acknowledges support from a Multidisciplinary Research on the Coronavirus and its Impacts (MRCI) grant from UC Santa Barbara. The Australian Seismometers in Schools data used in this research are supported by AuScope, enabled by the Australian Commonwealth NCRIS program. A.O. acknowledges support from the project RESIST, funded by the Belgian Federal Science Policy (contract SR/00/305) and the Luxembourg National Research Fund

Published
2020

48. Core Formation and Geophysical Properties of Mars.

Author

Brennan MC, Fischer RA, and Irving JCE

Abstract

The chemical and physical properties of the interiors of terrestrial planets are largely determined during their formation and differentiation. Modeling a planet's formation provides important insights into the properties of its core and mantle, and conversely, knowledge of those properties may constrain formational narratives. Here, we present a multi-stage model of Martian core formation in which we calculate core-mantle equilibration using parameterizations from high pressure-temperature metal-silicate partitioning experiments. We account for changing core-mantle boundary (CMB) conditions, composition-dependent partitioning, and partial equilibration of metal and silicate, and we evolve oxygen fugacity ( f O 2 ) self-consistently. The model successfully reproduces published meteorite-based estimates of most elemental abundances in the bulk silicate Mars, which can be used to estimate core formation conditions and core composition. This composition implies that the primordial material that formed Mars was significantly more oxidized (0.9-1.4 log units below the iron-wüstite buffer) than that of the Earth, and that core-mantle equilibration in Mars occurred at 42-60% of the evolving CMB pressure. On average, at least 84% of accreted metal and at least 40% of the mantle were equilibrated in each impact, a significantly higher degree of metal equilibration than previously reported for the Earth. In agreement with previous studies, the modeled Martian core is rich in sulfur (18-19 wt%), with less than one weight percent O and negligible Si. We have used these core and mantle compositions to produce physical models of the present-day Martian interior and evaluate the sensitivity of core radius to crustal thickness, mantle temperature, core composition, core temperature, and density of the core alloy. Trade-offs in how these properties affect observable physical parameters like planetary mass, radius, moment of inertia, and tidal Love number k 2 define a range of likely core radii: 1620-1870 km. Seismic velocity profiles for several combinations of model parameters have been used to predict seismic body-wave travel times and planetary normal mode frequencies. These results may be compared to forthcoming Martian seismic data to further constrain core formation conditions and geophysical properties.

Published
2020
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49. Seismically determined elastic parameters for Earth's outer core.

Author

Irving JCE, Cottaar S, and Lekić V

Abstract

Turbulent convection of the liquid iron alloy outer core generates Earth's magnetic field and supplies heat to the mantle. The exact composition of the iron alloy is fundamentally linked to the processes powering the convection and can be constrained by its seismic properties. Discrepancies between seismic models determined using body waves and normal modes show that these properties are not yet fully agreed upon. In addition, technical challenges in experimentally measuring the equation-of-state (EoS) parameters of liquid iron alloys at high pressures and temperatures further complicate compositional inferences. We directly infer EoS parameters describing Earth's outer core from normal mode center frequency observations and present the resulting Elastic Parameters of the Outer Core (EPOC) seismic model. Unlike alternative seismic models, ours requires only three parameters and guarantees physically realistic behavior with increasing pressure for a well-mixed homogeneous material along an isentrope, consistent with the outer core's condition. We show that EPOC predicts available normal mode frequencies better than the Preliminary Reference Earth Model (PREM) while also being more consistent with body wave-derived models, eliminating a long-standing discrepancy. The velocity at the top of the outer core is lower, and increases with depth more steeply, in EPOC than in PREM, while the density in EPOC is higher than that in PREM across the outer core. The steeper profiles and higher density imply that the outer core comprises a lighter but more compressible alloy than that inferred for PREM. Furthermore, EPOC's steeper velocity gradient explains differential SmKS body wave travel times better than previous one-dimensional global models, without requiring an anomalously slow ~90- to 450-km-thick layer at the top of the outer core.

Published
2018
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