Presented to: Infrasound Technology Workshop Tokyo, Japan

1
Presented toInfrasound Technology
WorkshopTokyo, Japan

• PTS Experimental Infrasound Array
• John Coyne1, Nicolas Brachet1, Paola Campus2,
  Pavel Martysevich2
  
• 1Software Applications Section
• International Data Centre Division
• 2IMS Installation and Certification Group
• International Monitoring System Division
• Preparatory Commission for the Comprehensive
• Nuclear-Test-Ban Treaty Organization
• Provisional Technical Secretariat
• Vienna International Centre
• P.O. Box 1200
• A-1400 Vienna
• Austria

2

• Outline
• Why?
• What?
• How?
• Where?
• When?
• Summary

3

• Why?
• Processing technique used at the IDC has
  demonstrated the exceptional capability of the
  IMS network for detecting a wide variety of
  signals
• Signals include microbaroms, ocean surf,
  mountain associated waves, thunderstorms,
  meteorites, avalanches, aurora, rockets,
  aircraft, mine blasts, accidental explosions,
  industrial noise
• Unlike earthquakes in the case of seismic data,
  few infrasound signals are energetic enough to be
  detected on a global scale by the IMS network
  
• Detection technique used at the IDC is well
  adapted for detecting infrasound signals,
  including cases of very weak signals
  
• The counterpart of such capability is the large
  number of genuine signals from a wide variety of
  sources
  
• It is important to understand and categorize
  these infrasound signals
  

4

• Understanding and Categorizing Infrasound
  Signals
  
• Infrasound Reference Event Database (IRED)
  Objective
  
• Collect, review and document infrasound events of
  special interest
  
• Archive the data for each event into database
  tables
  
• Use IRED for training, testing and validation
  purposes
  
• Inventory
• IRED contains 311 events grouped in 10 categories
  (Nov 2007)

5

• Understanding and Categorizing Infrasound
  Signals
  
• The database contents are limited due to
• difficulties in collecting metadata about the
  sources, as well as
  
• limited number of observations
• One common procedure is to identify events
  originating from a given azimuth, and use
  available information (e.g., news, Google Earth,
  etc.) to look for the potential source(s)
• This can lead to one or more hypotheses, which
  requires confirmation and further investigation
  
• In order to test such hypotheses, the PTS is
  procuring a portable IMS-type infrasound array
  that can be temporarily deployed in a region of
  interest

6

What?

• Experimental Array Minimum Specifications
• (from
  CTBT/PC/II/1/Add.2/Appendix X)
  

7

• Experimental Array Equipment Geometry
• Each of the 4 sites consists of
• Microbarometer
• Digitizer with storage (3 months)
• Power supply (batteries and solar panels)
• Wind reduction system
• Met data recorded at the central element
• One set of spare equipment

Geometry of 4-element infrasound array
8

• Experimental Array Equipment Housing
• Figure showing the organization of the electronic
  equipment in the plastic box and their
  connection to the external devices

9

• Experimental Array Wind Reduction System
• 
  Rosette filter configuration
  
• Six porous hoses
• Each hose 15 metres long

10

• Experimental Array Equipment List

11

How?

• Conceptual Method of Work
• Observation or idea
• Discussion between PTS and prospective
  participants
  
• Plan the project (dates, duration, locations,
  logistics, etc)
  
• Decision made concerning the proposal
• Exchange of letters (necessary paperwork)
• Provide equipment (and or analysis) training to
  participants
  
• Ship equipment to Country X
• Transport of equipment and participants to field
  location
  

12

• Conceptual Method of Work
• Field observations (one or multiple sites)
• Analyze data
• Transport equipment to PTS
• Document findings in a report
• Present and discuss results at Infrasound
  Workshop
  
• Feed Infrasound Reference Event Database
• NOTE
• This list is preliminary, and discussion is
  welcome!
  

13

Where?

• Candidate Scenarios
• Participate in controlled experiments
• (e.g., planned explosions or field campaigns)
• Test different field techniques and their effect
  on data processing
  
• (e.g., different noise reducing systems)
• Investigate infrasound sources recorded by IMS
  stations
  

14

• Source Investigation for an IMS station
• Install IMS station
• Observe reoccurring signals at IMS station
• Hypothesize potential sources of infrasound
  signals
  
• Propose experimental array deployment to
  distinguish between multiple potential sources or
  to verify a potential source
  

Experimental Array
Observed Azimuth
Potential Source
IMS station
15

• When?
• The hardware is currently in the procurement
  process
  
• Contract signature is expected before the end of
  2007
  
• Equipment should be available in 2Q 2008
• First observations in 3Q 2008
• Report first results at the next Infrasound
  Workshop
  

16

• Expected Benefits
• The experimental array will provide a way to
  investigate and confirm infrasound sources
  
• Provide additional meta-data for the Reference
  Event Database
  
• The experimental array can also be used in
  controlled experiments for improving techniques
  
• When participants will gain experience with the
  equipment, data analysis and interpretation, and
  project management
  
• The results will increase our understanding of
  infrasound sources
  

17

• Summary
• A sound understanding of infrasound sources is
  essential for interpreting infrasound signals
  
• Many genuine signals of unknown origin are
  routinely observed at IMS infrasound station
  
• The experimental array is expected to assist in
  understanding and categorizing infrasound
  signals
  
• Equipment is being procured, and first experiment
  should take place in mid-2008
  
• Initial results should be presented at the next
  Infrasound Workshop
  
• Interested parties should contact us concerning
  future collaboration