Relating large scale volcanic flank mass movements to the possible role and existence of water on Mars.email@example.com
There is a long recorded history of large terrestrial volcanoes exhibiting flank instability and collapse (McGuire et al, 1996). Simply put, volcanoes can only grow so large before they become unstable and collapse. There are a wide variety of causal mechanisms cited for these collapses but many involve the role of water, eg., changing sea levels (e.g. Carracedo et al., 1999), increases in pore pressures (e.g. Day, 1996), or the role of water in creating weak, deformable substrates (e.g. Van Wyk De Vries and Borgia, 1996). On Mars, there are also volcanic edifices, some of which have undergone flank collapse (Figure 1), but, their scale is quite different. The large Martian edifices have heights that dwarf their terrestrial counterparts. The Tharsis region contains the most clustered volcanic activity on Mars, formed mainly by the products of five volcanoes. Albas Mons, Olympus Mons, and the three Tharsis Montes—Ascraeus, Pavonis, and Arsia—with edifice heights of 10–22km. What is it that allows the Martian edifices to remain stable at heights far greater than their terrestrial counterparts? For one, there is lower gravity on Mars, so weight of the edifice will be less. The Martian lithosphere is much thicker than that of Earth, which may enable it to support much taller structures (Heap et al., 2017). There may have been no water present on Mars when volcanic edifices were growing, meaning that the destabilising effects of water were not encountered. Yet there are landforms on the flanks of these volcanoes (Figure 2), such as so-called “sinuous rilles”, which suggest running water was present at some point during their development (Murray et al., 2010; Byrne et al., 2012)—and so the role of water in these volcanoes’ evolution, and its control on flank collapse, remains an open question.
|Figure 1. High Resolution Stereo Camera nadir image mosaic of Tharsis Tholus, a “small” ~8 km-high edifice within the Tharis region that clearly shows the four large scarps (two to the east and two to the west) that characterize sector collapse. The colours correspond to slope angle. Image from Platz et al., 2011.|
The main objectives of this project are i) to analyse whether there is any relationship between sites of large-scale volcanic instability on Mars and areas of suspected historical ground or surface water, and ii) to account for the role of groundwater, where present, on the structural stability and evolution of large Martian shields. This will be achieved through an integrated programme of:
- Remote sensing: On Earth, studies of volcano instability are often hampered by the fact that it is a very geologically active planet. This is not the case on Mars, where surface features are extremely well preserved. This preservation, combined with the recent availability of extremely high-resolution imagery, makes it possible to conduct very detailed analysis of the Martian surface. Key data include High Resolution Stereo Camera (HRSC) and Context Imager (CTX) image data sets, as well as the Mars Orbiter Laser Altimeter (MOLA) topographic basemap.
- Rock mechanics: Current knowledge of the mechanical properties of Martian rocks and more importantly rock-masses is limited. This is a key missing parameter and it will be essential to gain a better understanding of these properties through a combined programme of theoretical, laboratory, and remote-sensing work.
- Modelling (Numerical and Analogue): Identifying the mechanism(s) of volcanic flank instability on Mars, and identifying whether common principles applied on Earth are applicable to Martian edifices regardless of effects such as mechanical properties, pore pressure, gravity etc., will be critical to understanding how these volcanoes evolve.
|Figure 2. An example of a sinuous rille on the flank of Ascraeus Mons. Note the river-like morphology of the channel, which may have been carved by flowing water, but which is also closely associated with volcanic landforms and lava flows.|
The student will be a member of an active and enthusiastic cohort of PhD researches at the University of Leeds and will be encouraged to become a part of the Planetary Exploration, Volcanology and Engineering Geology and Hydrology research groups. The successful candidate will receive training in research methodology in addition to remote sensing, rock mechanics, and numerical modelling skills. There will be the opportunity to present research findings at national and international conferences and workshops. In addition, the candidate will spend an extended period of time at NC State University under the supervision of Dr Paul Byrne to develop research ideas, collaborate with other staff, and gain experience in analogue modelling techniques with the NC State Planetary Research Group.
Byrne, P. K. et al., 2012. A volcanotectonic survey of Ascraeus Mons, Mars. Journal of Geophysical Research, 117, E01004.
Carracedo, J.C., et al., 1999. Giant Quaternary landslides in the evolution of La Palma and El Hierro, Canary Islands. Journal of Volcanology and Geothermal Research, 94, 169-190.
Day, S.J., 1996. Hydrothermal pore fluid pressure and the stability of porous, permeable volcanoes. In: McGuire, W.J., Jones, A.P., and Neuberg, J., (Eds), 1996. Volcano instability on the Earth and other planets. London: Geological Society London Special Publication, 110
Heap, M.J., Byrne, P., and Mikhail, S., 2017. Low surface gravitational acceleration of Mars results in a thick and weak lithosphere: Implications for topography, volcanism, and hydrology. Icarus, 281, 103-114.
Murray, J. B., et al., 2010. Late-stage water eruptions from Ascraeus Mons volcano, Mars: Implications for its
structure and history. Earth and Planetary Science Letters, 294, 479–491.
Platz, T., et al., 2011. Vertical and lateral collapse of Tharsis Tholus, Mars, Earth and Planetary Science Letters, 305, 445-455.
Van Wyk De Vries, B., and Borgia, A., 1996. The role of basement in volcano deformation. In: McGuire, W.J., Jones, A.P., and Neuberg, J., (Eds), 1996. Volcano instability on the Earth and other planets. London: Geological Society London Special Publication, 110.
Related undergraduate subjects:
- Earth science
- Geological science
- Geophysical science
- Mechanical engineering