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Monitoring - Coggle Diagram

- - - - Direct method were a gas tight bottle containing caustic solution is placed over a fumarole (volcanic vent)
      - SO2/CO2 dissolve while HE and CO collect and can be used for analysis
    - - Accumulation chamber placed on vent to measure the flux of diffuse gases like CO2
      - Requires extensive grid based surveys
    - - UV spectroscopy
        
        Uses scattered UV light from daytime sky to measure flux of SO2 per day
        
        Can be mounted on drones, vehicles or scanning platforms
      - Infrared spectroscopy
        
        Uses an IR source like a hot lake
        
        Measure absorption of different gases like HO0 or CO2
    - - Small cheap electronic sensors
      - Real-time data on concentration of certain gases
      - Can be deployed near crater or drones
  - - - UAVs can mitigate this though can be damaged
  - - - Increase means fresh mantle-driven magma has entered the chamber
      - Ontake Japan 2014
- - - - Instruments that record ground shaking
      - Often use broadband sensors crucial for low frequency signals characterise of fluid movement in volcnaoes
      - Data analysis
        
        Event counting
        
        Measure of activity but can be bad as it counts all activity equally
        
        Don't use in isolation
        
        RSAM real time Seismic Amplitude Measurement
        
        More sophisticated
        
        Provides real-time continuous measure of seismic energy being released
        
        Good for intensity of volcanoes
        
        Spectrograms
        
        Visual representations of seismic frequencies overtime
        
        Insight into fluid dynamics
- - - - Highly sensitive
      - Measures changes in ground slope
      - Can detect changes as small as equivalent raising end of a 1km bar by 1 mm
    - - Continuously operating GPS stations can measure position with millimetre accuracy
      - Change = deformation
    - - Powerful space-based technique using radar satellites
        
        Sends signal to surface and records phase of return signal
        
        Compares changes in signals
        
        Equivalent to lots of GPS stations