Calculating Dome Thickness as a Function of Radial Distance for - PowerPoint PPT Presentation

1 Calculating Dome Thickness as a Function of Radial Distance for Cryovolcanic Domes on Europa ALYSSA MILLS

2 Cryovolcanism Definition: volcanoes that erupt volatiles instead of u molten rock Cryovolcanism creates domes through: u u Diapirism u Extrusion of viscous fluid Top figure: Diapirism and cryomagmatism schematic, taken from Fagents et al., 2003 Bottom left figure: Examples of cryovolcanic domes formed via diapirism or cryomagmatism, taken from Quick et al., 2017

3 Motivation Understand the mechanisms of u cryovolcanism Find if analogous with siliceous u volcanism on Earth u Run models made for siliceous volcanism to cryovolcanism Gauge the activity on Europa u Understand the role of tidal heating on u Europa Lava dome on Earth taken from USGS

4 Previous Work: Quick et al., 2017 Created the method to u measure the emplacement and relaxation of cryolava domes u Tests multiple rheological parameters, times, and radial distances Relaxation time of domes: 3.6 u days to 7.5 years Models are consistent with the u 2 sets of domes with radius of 3 km Dome thickness as a function of radial distance using four time steps taken from Quick et al., 2016

5 My Work: Sample Selection Location: Southern u region near Libya Linea Cryovolcanoes u formed from effusive processes 1 Radius for Dome 1: u 2 km Height for Dome 1: u 25 m

6 Sample Selection Continued Radius for Dome 2: 1.9 km u Height for Dome 2: 32 m u 2

7 My Work Set up model to run six time steps u based on: ./) + - '( . . u ℎ 𝑠, ⍬ = ⁄ ) 5/7 1 − - - ⁄ ) 5/7 )*+ , (.01 2 + , (.01 2 u Ends at final dome radius determined from cross-sections Run model with different boundary u conditions u E.g. Time-dependent viscosity

8 Dome 1 Closest Matches A.) t=12 hours u B.) t=12 hours u C.) None u D.) t=3 days u Overall closest match occurs at: u u t= 12 hours u Viscosity: 10 ; <- = u Results in final radius of 2001 m and thickness of 23 m

9 Dome 2 Closest Matches A.) t = 12 hours u B.) t= 1.5 days u C.) None u D.) t=3 days u Overall closest match occurs u at: u t= 1.5 days u Viscosity: 10 ; <- = u Results in final radius of 2001 m and thickness of 33 m

10 Implications Consistent with Quick et al.’s results where u smaller domes have shorter relaxation times These domes are smaller due to recent u emplacement Expected to grow with time u Use these smaller domes for more u accurate initial dome radii and thicknesses for model Short relaxation time implies current active u cryovolcanism Artist depiction of cryovolcanism on Europa, taken u Consistent with Roth et al., 2014’s prediction from NASA/JPL/Ted Stryk; NASA/JPL/Caltech

11 Questions?

12 Future Work Calculate dome relaxation with u asymmetry Consider other aqueous solutions for u better accuracy Apply models to other icy bodies with u cryovolcanism u E.g. Pluto Close-up of suspected cryovolcanoes on Pluto’s southern terrain, taken from NASA

13 Supplement Material: Boundary Conditions