Detection from Space of Active Volcanism on Earth and, Potentially, on Venus and Rocky Exoplanets

Transcription

1 Detection from Space of Active Volcanism on Earth and, Potentially, on Venus and Rocky Exoplanets Pete Mouginis Mark Hawaii Institute Geophysics and Planetology University of Hawaii

2 Overview Styles of Eruption on Earth Lava flows Explosive eruptions Detection of Terrestrial Eruptions from Space Thermal features Lava Flows Ash and Gas Explosive Eruptions Venus Eruptions? Radar and multi spectral Exoplanet Eruptions? Thermal detection Io analog Explosive eruptions planets with atmospheres Explosive eruptions planets without atmospheres

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5 Thermal Detection from Weather Satellites

6 Detection of Active Lava flows from Space Spectral Radiance as a function of wavelength

7 Detection of Active Lava flows from Space Spectral Radiance as a function of wavelength

8 Kilauea, Hawaii Greatest Thermal Flux

9 Typical Io Lava Lake Compared to Kilauea

10 Radiant output of Earth s volcanoes, Wright et al. (2015). Geophys. Res. Lttrs, vol. 42

11 Lava eruption style and composition from temperature data The temperature distributions can be explained in terms of averageageofthelavaexposed (e.g., fountains have a high temperature peak because of continual exposure of new lava; domes do not)

12 Lava eruption style and composition from temperature data

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14 Characteristics of Eruption Clouds

15 Movement of Mt. Spurr, Alaska, Ash Cloud

16 2 nd Largest Eruption in 20 th Century, Mount Pinatubo

17 UV Detection of Mt. Pinatubo SO2, June 16, 1991

18 Largest Historic Explosive Eruptions on Earth The Economist, April 11 th, 2015

19 What About Active Volcanism on Venus?

20 Previous Hints at Active Volcanism Episodic Injection of Sulfur Dioxide into Atmosphere. Esposito (1984), Science 223, High radar emissivity at high elevations, such as summit of the volcano Maat Mons. Robinson and Wood (1993), Icarus 102, Thermal emissivity measurements of surface by the Venus Express Visible and Infrared Thermal Imaging Spectrometer. Smrekar et al., (2010) Science Enhanced microwave thermal emission, potentially due to very recent lava flow emplacement. Bondarenko et al. (2010), Geophys. Res. Lttrs. 37. doi: /2010GL

21 So, how might we really find current activity? Anomalous spectral properties at volcano summit

22 Insights into Heat Flow from Interior: Large Shield Volcanoes on Venus

23 Earth Based Radar Images of Venus: Eruption Detection Campbell and Campbell continue to collect new radar images of Venus suitable for change detection? Arecibo Observatory

24 20+ year Magellan vs. post Magellan Comparisons: Pu u O o Comparison SIR C C Band April 1994 RADARSAT C Band June 2010

25 20+ year Magellan vs. post Magellan Comparisons: Pu u O o Comparison SIR C C Band April 1994 RADARSAT C Band June 2010

26 Can We Detect New Lava Flows from Time Series Data?

27 Alternative Method: Coherence Mapping Detects New lava flows at Kilauea Volcano, October 1994 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 Zebker et al., Geology vol. 24

28 Radar Interferometry can also detect small changes through repeatpass radar measurements: Volcano Deformation

29 InSAR detection of ground deformation: Example from Kilauea volcano, Hawaii

30 What is the Possibility of Detecting Exoplanet Active Volcanism?

31 Important to Consider Size of the Eruption

32 Power Detected for Volcanic Hot Spots on Io

33 Volcanic Eruptions on Io from Keck Telescope, Feb. 2001

34 Largest Lava Flows on Earth in Last 300 m yrs. Deccan Traps, India. ~65 million years old

35 Exoplanet Explosive Eruptions Atmosphere Spectral detection of SO2 or ash?

36 Explosive Eruptions on Exoplanets Simulation of Mt. Pinatubo class Explosive Eruptions Issues: How to recognize silicate ash against a silicate surface? Would atmospheric sulfur dioxide be a better identifier?

37 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

38 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

39 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

40 Final Thought: How do we distinguish an eruption from an impact event? Impact melt pond could produce a thermal anomaly could mimic a big lava flow Ejecta thrown into air could mimic the spectral properties of an ash cloud