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Detection from Space of Active Volcanism on Earth and, Potentially, on Venus and Rocky Exoplanets
Pete Mouginis‐MarkHawaii Institute Geophysics and Planetology
University of Hawaii
• Styles of Eruption on Earth• Lava flows• Explosive eruptions
• Detection of Terrestrial Eruptions from SpaceThermal features – Lava FlowsAsh and Gas – Explosive Eruptions
• Venus Eruptions?Radar and multi‐spectral
• Exoplanet Eruptions?Thermal detection ‐ Io analogExplosive eruptions ‐ planets with atmospheresExplosive eruptions ‐ planets without atmospheres
Overview
The temperature distributionscan be explained in terms ofaverage age of the lava exposed(e.g., fountains have a hightemperature peak because ofcontinual exposure of new lava;domes do not)
Lava eruption style and composition from temperature data
Previous Hints at Active Volcanism
Episodic Injection of Sulfur Dioxide into Atmosphere. Esposito (1984), Science 223, 1072 – 1074.
High radar emissivity at high elevations, such as summit of the volcano Maat Mons. Robinson and Wood (1993), Icarus 102, 26 – 39.
Thermal emissivity measurements of surface by the Venus Express Visible and Infrared Thermal Imaging Spectrometer. Smrekar et al., (2010) Science 328.605 – 608.
Enhanced microwave thermal emission, potentially due to very recent lava flow emplacement. Bondarenko et al. (2010), Geophys. Res. Lttrs. 37. doi: 10.1029/2010GL045233.
Earth‐Based Radar Images of Venus: Eruption Detection
Arecibo Observatory
Campbell and Campbell continue to collect new radar images of Venus – suitable for change detection?
SIR‐C C‐Band April 1994 RADARSAT C‐Band June 2010
20+ year Magellan vs. post‐Magellan Comparisons:Pu‘u ‘O’o Comparison
SIR‐C C‐Band April 1994 RADARSAT C‐Band June 2010
20+ year Magellan vs. post‐Magellan Comparisons:Pu‘u ‘O’o Comparison
Geometry of repeat‐pass interferometry for coherent change detection: A measure of the path length difference. Ideally, the baseline should be zero, so that path differences are only due to motion
Alternative Method: Coherence Mapping Detects New lava flows at Kilauea Volcano, October 1994
Zebker et al., 1996. Geology vol. 24
Radar Interferometry can also detect small changes through repeat‐
pass radar measurements:
Volcano Deformation
Explosive Eruptions on ExoplanetsSimulation of Mt. Pinatubo‐class Explosive Eruptions
Issues: • How to recognize silicate ash against a silicate surface?• Would atmospheric sulfur dioxide be a better identifier?
Exoplanet Explosive Eruptions – No Atmosphere
Expect widespread new occurrence of plume deposits on surface.
Io shows us that deposits will merge with background. Hinders spectral identification
Time‐Series Data Are Critical!
A single observation is not sufficient. Look for changes on an Exoplanet• Thermal flux from lava flows is best detected at night, but day/night comparisons would be optimal
• Confident plume detection would require before/during/after data
Time‐Series Data Are Critical!
A single observation is not sufficient. Look for changes on an Exoplanet• Thermal flux from lava flows is best detected at night, but day/night comparisons would be optimal
• Confident plume detection would require before/during/after data