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Australian Infrasound Resources and Projects

Australian Infrasound Resources and Projects. David Brown Geoscience Australia ph: +61-2-6249-9024 Email: David.Brown@ga.gov.au. July 2003. 1. Outline. Australian Resources Geoscience Australia Australian National University Australian Projects Nuclear Monitoring Volcano Monitoring

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Australian Infrasound Resources and Projects

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  1. Australian Infrasound ResourcesandProjects David Brown Geoscience Australia ph: +61-2-6249-9024 Email: David.Brown@ga.gov.au July 2003 1

  2. Outline • Australian Resources • Geoscience Australia • Australian National University • Australian Projects • Nuclear Monitoring • Volcano Monitoring • Bird Migration • GA’s Projected Capability (12-18 months) • Possible NSF Funded Infrasound Projects 2

  3. Resources • Geoscience Australia • Operating 4 of the 5 Australian IMS infrasound stations • I06AU Cocos. Is, operational Sept. 2005 • I05AU Bucklands, Tas currently operational, sending data to Vienna • I04AU Shannon, WA, operational Mar. 2005 • I03AU Davis, Antarctica, operational Dec. 2006 • Likely to provide assistance/advice on theRabaulinstallation Rabaul Tennant Creek July 2003 Shannon 3 Cocos Is. Davis Bucklands

  4. Resources • Geoscience Australia • Responsible for processing data from all 5 Australian IMS infrasound stations • Recently (3 months ago) initiated processing of IMS infrasound data (I07AU) • Automatic signal detection (INFER) • Analyst review • High-speed numerical modeling of fluid flow and wave propagation problems • Beowulf cluster (coming) July 2003 4

  5. Resources • Australian National University • Operating 1 of 5 Australian IMS infrasound stations • I07AU Tennant Creek, NT currently operational, sending data to Vienna • 2 years of archived data • 27 years of (largely inaccessible) archived data from earlier WRAI array July 2003 5

  6. 1980 Chinese Nuclear Detonation, Lop Nor, 4 Mt Gravity Acoustic Acoustic Acoustic 75 microbar 0 60 30 120 90 [after Christie] minutes

  7. Resources • Australian National University • World class supercomputer facility • Developed INFER automatic infrasonic detection algorithm July 2003 7

  8. Acoustic signal from shuttle launch STS-96 recorded at DLIAR, Los Alamos a significant signal Distinct lack of correlation amplitude Signal presence is obvious to the human eye due to the dominant azimuth and trace velocity INFER: Motivation STS-96 [DLIAR, Los Alamos]

  9. INFER: the Hough Transform Pairs of points (xi,yi) get mapped to the point (m,t) where Image Space, S Parameter Space, P Hough Transform

  10. INFER: the Hough Transform Parameter Space, P Image Space, S STS-96 Hough Transform [DLIAR, Los Alamos]

  11. INFER: 3D array geometry 3.5 3 2.5 Sz (s/km) 2 1.5 1 radius = acoustic slowness 3 2 3 2 1 1 0 0 -1 -1 Sy (s/km) -2 -2 Sx (s/km) -3 -3

  12. INFER: detection results

  13. INFER: detection results

  14. INFER • makes a single detection per phase • Fortran code complete (minor bugs) • C-code ready for testing • dynamically populates various CSS database tables • arrival • detection • infra_features • lastid • wfdisc • psd_frequency • infra_psd • infra_noise_models • determines PSD for every 1/2 hour for every channel

  15. INFER: PSD measurement

  16. INFER: PSD noise models I10CA high noise model I10CA low noise model

  17. INFER: PSD measurement I33MG high noise model I33MG low noise model

  18. Projects • Nuclear Monitoring • Satisfying Australian Government’s obligations to monitor compliance of the CTBT • near-real time processing of data from 5 IMS infrasound stations • Automatic signal detection • INFER detection algorithmcurrently operational at Geoscience Australia • Automatic source location • operational by the end of 2003 • Analyst review • recently initiated, ongoing development of analyst procedures • Source characterisation and discrimination analyses • localised large-scale open-cut mining activity • Tripartite sub-net: I04AU, I05AU, I07AU uniquely positioned to do source location analyses July 2003 18

  19. Projects • Volcano Monitoring • Prompted by a call by the Airlines to develop a multi-technology ‘early warning’ system for volcanic ash. • ‘Consortium’ of Australian companies and government organisations formed to determine if it is possible to create a multi-technology volcanic ash monitoring system for aircraft • Vulcan-AUS group: • Bureau of Meteorology • Qantas • Geoscience Australia • CSIRO • Airservices Australia • Formed in mid-1980’s in response to a volcanic ash encounter of a British Airways 747 over Indonesia. July 2003 19

  20. Projects • Volcano Monitoring • GA’s role: • Perform usual near-real time automatic signal detection of IMS infrasound array data • ‘Siphon’ off detections from a near-real time event list that are within a few degrees of known volcanic activity • email event list to interested persons • microbarom false alarms may be significant • seasonal erosion of propagation ducts will also occur July 2003 20

  21. Projects • Bird Migration • does infrasound have a role to play in the migration of birds to wetland areas during major flooding events ? • GA’s role: • systematically process data during periods of known flooding and search for anomalous infrasonic signals July 2003 21

  22. GA’s Projected Capability 12 to 18 months • Real-time processing of data from several infrasound arrays: • Tennant Creek, Northern Territory • Hobart, Tasmania • Shannon, Western Australia • Generation of an automatic detection list • various CSS database tables dynamically populated • Rudimentary source location of GT events • use crossing azimuths, time used to preserve causality • use observed departures from great-circle to refine source location procedure July 2003 22

  23. Possible NSF funded infrasound projects • Volcano Early Infrasound Warning System (VEIWS) • need to perform research that will determine if a significant early warning for volcanic ash can be reliably given via a precursory infrasound signal • do magma chamber rumbles generate atmospheric acoustic signals prior to venting ? • What instrumentation is required to measure the signal ? • What are the signal chracteristics ? • Will require near-real time infrasound data processing • May require development of a sophisticated real-time numerical microbarom filter • A starting point may be Olson’s Analytical signal technique July 2003 23

  24. Possible NSF funded infrasound projects • ‘Grand-Challenge’ numerical infrasound algorithm • Will: • solve the basic Navier-Stokes equations on an ellipsoid • be fully non-linear • be non-hydrostatic • include acoustic-gravity modes • use as input NRL climatological and environmental data • accurately model physics from a highly-nonlinear source region to the completely linear far-field • Suitable for operation on the: • ‘Earth Simulator’ supercomputer • A Beowulf cluster • Will include • topography • acoustic radiation from the ocean surface • solar tides July 2003 24

  25. Possible NSF funded infrasound projects • ‘Grand-Challenge’ numerical infrasound algorithm • Purpose: • Infrasound can ‘catch up’ with all other geophysical modelling efforts. • assess the validity of other modelling procedures: • ray tracing • modal calculations • parabolic approximation • Better understand: • Microbarom radiation and to what extent it heats the atmosphere • The phenomenon of Mountain Associated waves • Acoustic scattering and diffraction • Accurate source location July 2003 25

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