Rock physics analysis of geophysical data from Mars
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Project description
Large volumes of liquid water transiently existed on the surface of Mars more than 3 billion years ago. Much of this water is hypothesized to have been sequestered in the subsurface or lost to space (Wright et al., 2024). If there is water on Mars then human colonization of Mars may one day be possible.
The inSight mission to Mars involved the collection of large amounts and geophysical data from Mars and some of these data are available in the public domain. This includes seismic data and velocity profiles obtained from inversion of surface waves (Carrasco et al., 2023; Wright et al., 2024; Katayama and Akamatsu, 2024).
In this project, the student should use rock physics models and Bayesian inversion to identify combinations of lithology, liquid water saturation, porosity and pore shape consistent with the constrained mid-crust seismic velocities and gravity near the inSight lander (Wright et al., 2024). Some studies suggest that a mid-crust composed of fractured igneous rocks saturated with liquid water best explains the existing data (Wright et al., 2024). However, other studies suggest that completely different models can also explain the data (Carrasco et al., 2023, Katayama et al., 2024; Avseth, 2024, personal communication). Therefore, there is an important need for a critical examination of published rock physics analysis in addition to the testing of new approaches.
The student should investigate the use of a general T-matrix approach to rock physics in conjunction with Bayesian inversion methods in this context (Ali and Jakobsen, 2011). More specifically, models of dry and water liquid-saturated fractured porous media should be developed and applied in this context. The uncertainty of the rock physics inversion results should be investigated via Monte Carlo simulation (Ali and Jakobsen, 2011). A comparison of results based on inclusion models for fractured porous media and contact theory can also be performed (Jakobsen and Chapman, 2009; Avseth, 2010; Ali and Jakobsen, 2011).
Proposed course plan during the master's degree (60 ECTS)
GEOF211 Numerical Modelling
GEOV218 Rock Physics
GEOV276 Introduction to Theoretical Seismology
GEOV277 Signal analysis and inversion in the earth sciences
GEOV375 Advanced applied seismic analysis
Prerequisites
Good background in Matlab or Phyton programming.An interest in applied mathematics and quantitative aspects of geophysics.
This project gives training highly relevant for work in industry as well as general training in the scientific method and critical thinking.
Field-, lab- and analysis work
The student will perform a rock physics analysis of seismic data and processing results from Mars. More specifically, geophysically data from the Insight mission.
NB! This project has not yet been approved by the research group and program board.
References
Carrasco, S., Knapmeyer-Endrun, B., Margarin, L., Xu, Z., Joshi, R., Schimmel, M., Stutzmann, E., Charalambous, C., Lognonne, P. and Bannerdt, W.B., 2023. Constraints for the Martian Crustal Structure From Rayleigh Waves Ellipticity of Large Seismic Events
Geophysical Research Letters, 50, 1-10.
Wright, V., Morzfield, M. and Manga, M., 2024. Liquid water in the Martian mid-crust. PNAS, Earth, Atmosphere and Planetary Sciences, 121, 1-3.
Katayama, I. and Akamatsu, Y., 2024. Seismic discontinuity in the Martian crust possibly possibly caused by water-filled cracks. Geology, https://doi.org/10.1130/G52369.1
Jakobsen, M. and Chapman, M., 2009. Unified theory of global and squirt flow in cracked porous media. Geophysics, 74, WA65-WA76.
Ali, A. and Jakobsen, M., 2011. On the accuracy of Rugers approximations for reflection coefficients in HTI media: Implications for fracture density and orientation from seismic AVAZ data. J. Geophysical. Engineering, 8, 372-393.
Avseth, P. and Mukerji, T. and Mavko, G., 2010. Quantitative seismic interpretation. Cambridge University Press.