1. EART193 Planetary Capstone
Francis Nimmo

2. Topics
I want to cover a couple of topics which have both terrestrial and planetary applications:
Lava lakes are well-studied on Earth and also appear to exist on Io
Surface inflation by subsurface intrusions is also well-studied on Earth and has been applied to Venus

3. Terrestrial lava lakes
Patrick et al. 2016

4. Observations
Surface temperatures are roughly K (much less than magma temperature)
Typical surface velocities ~ 20 cm/s
Typical thickness of surface crust ~ 6 cm
We need some theory to explain these . . .

5. Constant viscosity convection
Vigour of convection is given by the Rayleigh number Ra:
A convecting fluid will consist of an interior in motion and a thermal boundary layer which is moving horizontally but not vertically. Heat is conducted across this layer of thickness d:
More vigorous convection will give thinner boundary layers (and higher heat fluxes). Note that d is independent of d.
The characteristic fluid velocity is given by

6. Conceptual lava lake model
Frad d
We can solve for the surface temperature Ts
How do our results compare with the observations?

7. What about Io?
Loki Patera as seen by Voyager 1 in March Numerous volcanic calderas and lava flows are visible. Loki Patera is the large shield‐shaped black feature in the lower center and is about 200 km in diameter. The bright whitish patches are probably freshly deposited SO2 frost. The feature Loki was the source of two volcanic plumes during the Voyager epoch. Photo credit: NASA.
IF THIS IMAGE HAS BEEN PROVIDED BY OR IS OWNED BY A THIRD PARTY, AS INDICATED IN THE CAPTION LINE, THEN FURTHER PERMISSION MAY BE NEEDED BEFORE ANY FURTHER USE. PLEASE CONTACT WILEY'S PERMISSIONS DEPARTMENT ON OR USE THE RIGHTSLINK SERVICE BY CLICKING ON THE 'REQUEST PERMISSIONS' LINK ACCOMPANYING THIS ARTICLE. WILEY OR AUTHOR OWNED IMAGES MAY BE USED FOR NON-COMMERCIAL PURPOSES, SUBJECT TO PROPER CITATION OF THE ARTICLE, AUTHOR, AND PUBLISHER.
Journal of Geophysical Research: Planets Volume 111, Issue E9, E09002, 2 SEP 2006 DOI: /2006JE

8. Loki Patera is probably a lava “lake”
Image of Loki Patera showing the Davies [2003] temperature map with the location and inferred direction of motion of the resurfacing front noted. Also shown is the age of the surface and the crustal thickness. The active front, where crust is foundering and being replaced by new, hot lava, is probably to the NE of the area covered by the Galileo NIMS observation 32INTHLOKI01 obtained in October 2001 from which the Davies [2003] age‐temperature map was derived.
IF THIS IMAGE HAS BEEN PROVIDED BY OR IS OWNED BY A THIRD PARTY, AS INDICATED IN THE CAPTION LINE, THEN FURTHER PERMISSION MAY BE NEEDED BEFORE ANY FURTHER USE. PLEASE CONTACT WILEY'S PERMISSIONS DEPARTMENT ON OR USE THE RIGHTSLINK SERVICE BY CLICKING ON THE 'REQUEST PERMISSIONS' LINK ACCOMPANYING THIS ARTICLE. WILEY OR AUTHOR OWNED IMAGES MAY BE USED FOR NON-COMMERCIAL PURPOSES, SUBJECT TO PROPER CITATION OF THE ARTICLE, AUTHOR, AND PUBLISHER.
Journal of Geophysical Research: Planets Volume 111, Issue E9, E09002, 2 SEP 2006 DOI: /2006JE

9. Evidence for foundering?
Model 3 is the “foundering” model [after Rathbun et al., 2002].
IF THIS IMAGE HAS BEEN PROVIDED BY OR IS OWNED BY A THIRD PARTY, AS INDICATED IN THE CAPTION LINE, THEN FURTHER PERMISSION MAY BE NEEDED BEFORE ANY FURTHER USE. PLEASE CONTACT WILEY'S PERMISSIONS DEPARTMENT ON OR USE THE RIGHTSLINK SERVICE BY CLICKING ON THE 'REQUEST PERMISSIONS' LINK ACCOMPANYING THIS ARTICLE. WILEY OR AUTHOR OWNED IMAGES MAY BE USED FOR NON-COMMERCIAL PURPOSES, SUBJECT TO PROPER CITATION OF THE ARTICLE, AUTHOR, AND PUBLISHER.
Journal of Geophysical Research: Planets Volume 111, Issue E9, E09002, 2 SEP 2006 DOI: /2006JE

10. Surface temperatures Two-temperature fits
“Cold” part is probably cooled crust
“Hot” part is probably fissures
Hot component
Cold component
Orbit
Temp (K)
Area (km2)
Output (GW) G2
1394+/-25
0.46 99
769+/-25
5.8
116 G8
1362+/-78
0.20 39
549+/-19 31
161
C10
1077+/-13
1.6
122
544+/-7
24.4
121
E15
1369+/-141
0.42 94
625+/-43
15.4
133
E16
1353+/-46
0.63
120
649+/-16
15.9
160
C20
1300+/-71
0.41 66
588+/-8
25.4
172
Davies, Volcanism on Io, CUP, 2007

11. Periodic Behaviour?
Rathbun et al. 2002

12. “Mogi model” What happens if a magma body is intruded at depth? r d 2a
u = horizontal displacement
v = vertical displacement

13. 1d d d d v u er et
What would a plot of the strains look like? What would you predict for their surface expression?

14. S. America (Pritchard & Simons 1994)
Long Valley, CA
(Tizzani et al. 2009))

15. What about Venus?
Grindrod et al.
(2005)
Scale bar
100 km

17. Homework – Week 7 Write a ~1000 word chunk of your report
Due next Tues
No class on Thurs – use the time to write