1. Studying Volcanoes With InSAR: Where Have We Been and Where Are We Going? Howard Zebker, Cody Wortham Stanford University

2. 10 Years Ago: Where Were We? Anticipated several new space radar systems for monitoring and forecasting of volcanic events Developing inverse methods to reveal the details of faulting or pressure changes at depth, and better describe precise magma chamber geometries Beginning reliable interferometric imaging,m-scale resolution of mm-scale deformation over wide areas Proposed high-res stereo radar for 3-D topographic maps fast events, e.g. rapid dome growth Foresaw data collection over all of Earth’s 600 potentially active volcanoes weekly or even daily Designing satellite constellations in along-track interferometric formation to map flow velocities

3. Reality: What actually happened Anticipated several new space radar systems for monitoring and forecasting of volcanic events Developing inverse methods to reveal the details of faulting or pressure changes at depth, and better describe precise magma chamber geometries Beginning reliable interferometric imaging,m-scale resolution of mm-scale deformation over wide areas Proposed high-res stereo radar for 3-D topographic maps fast events, e.g. rapid dome growth Foresaw data collection over all of Earth’s 600 potentially active volcanoes weekly or even daily Designing satellite constellations in along-track interferometric formation to map flow velocities

4. Technology has advanced to where we know how to do this Want long wavelength, high resolution, rapid repeat times Systems beginning to reflect community knowledge Still waiting for the “perfect” system Reliable imaging

5. Longer wavelengths yield higher correlation Wortham et al., 2010 ALOS Kilauea interferogram: 460 day separation, 1490 m baseline

6. Time series volcano observationsEyjafjallajokull PS deformation Time series 1993-2000 SBAS deformation From Hooper, 2008

7. Precision of PS method PS performance PS image of San Andreas Fault - ERS satellite RMS error ~1 mm/yr PS spacing is ~1km

9. Pixel does not scintillate, is “persistent”

10. Bright scatterer perhaps less than rest of background

12. ALOS/PALSAR ALOS satellite, PALSAR radar instrument L-band, wavelength 24 cm Repeat period 46 days Multipolarization 10-20 m resolution Very high correlation Just ended successful mission

14. Repeat period 11 days

15. Multipolarization

16. 1-20 m resolution

17. Ideal for time-series observations

18. Current research … Most exciting area is time series analysis Modeling continues to advance Tandem satellites supersede previous desire for radar stereo New measurements and methods will yield new descriptors

19. Time series mimics GPS imaging From Lundgren et al.

20. Modeling of Yellowstone caldera Interpretation: Inflating sill Interferograms: C-band From Wicks et al., 2006

21. Modeling Uzon caldera, Kamchatka (a) Distributed opening model, (b) distributed crack model, (c) depth slice of model b Radarsat measurements 2000-2005 Lundgren and Lu, 2006

23. Highest activity from coincident increases

24. PDF derived from spaceborne data onlyFrom Patrick et al., 2006

27. … but some things still lacking Enabling technology is coverage, temporal and geographic Optimizing designs for InSAR Orbits: poor north retrieval System parameters High resolution, long wavelength helps Future mission prospect good/bad/?

31. Interferograms formed from each beam

32. MAI phase gives along-track displacement from differencing forward/backward interferogramsN. Bechor, PhD Thesis (2006)

33. Average north displacement using MAI North component of displacement averaged over all InSAR acquisitions

35. South America data show comprehensive coverage possible

36. 46 day repeat is too long- misses many signals

37. PALSAR data rate/volume too low to monitor 600 volcanoesFrom: Fournier et al., 2010

38. NASA DESDynI-R Mission Launch in 20XX L-band, potential 2 m resolution Free and open data policy Specifically designed for InSAR Volcano hazards one of the major science objectives Artist’s concept from JPL

39. Additional exciting missions ALOS-2 (Japan): L-band follow-on to ALOS, launch 2013?, 1-10 m resolution, 14 day repeat But likely will be commercially oriented with data hard to get Tandem-L (Germany): Similar in philosophy to Tandem-X, but companion to DESDynI, no money yet Sentinel-1 (ESA): C-band heir to Envisat, 12 day repeat, 5 m resolution, 201w? Launch There are others…

40. Summary and looking ahead InSAR continues to evolve better accuracy and temporal/spatial coverage Volcano hazard applications benefit Future satellites converging on ~12 day repeats and m-scale resolution Limiting factor is probably data policy- agencies still don’t get the science message and pursue commercialization If data are acquired, volcanologists will come