Detection from Space of Active on Earth and, … from Space of Active Volcanism on Earth and,...
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Transcript of Detection from Space of Active on Earth and, … from Space of Active Volcanism on Earth and,...
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