Volcanic Activity Monitoring and Prediction Notes

The Science of Prediction

Monitoring Volcanic Activity
  • Signs of Volcanic Activity: Scientists monitor five key indicators:
    • Eruption History: Historical data on past eruptions helps predict future activity.
    • Volcanic Gases: Changes in gas composition can signal imminent eruptions.
    • Heat and Hydrothermal Activity: Elevated temperatures may indicate moving magma.
    • Earthquakes: Increased seismic activity is often a precursor to eruptions.
    • Ground Deformation: Changes in the shape of the volcano can indicate magma movement.
Monitoring Tools
  • Observation Tools: Various instruments are used for monitoring volcanoes, often set up to operate autonomously due to the danger of eruptions.
  • Transmission of Data: Tools typically transmit data via radio signals to a field office or a Volcano Observatory.
  • U.S. Volcano Observatories: Includes five main locations operated by USGS and other organizations:
    • Alaska Volcano Observatory (AVO)
    • Hawaiian Volcano Observatory (HVO)
    • Cascades Volcano Observatory (CVO), Washington
    • Long Valley Observatory (LVO), California
    • Yellowstone Volcano Observatory (YVO), Montana
Examples of Eruptions
  • Mt. St. Helens: Erupted on May 18, 1980, where extensive monitoring helped save lives. This includes:
    • April 1980 monitoring that led to preparedness for the eruption.
    • Historical data supports the notion: “The Past is the Key to the Present.”
Types of Eruptions
  • Ash, Gas, and Steam Eruptions:
    • Caused by the release of trapped gases and steam.
    • Often detected by surface earthquakes and changes in gas levels.
  • Lava Flows:
    • Occur when magma leaks from the volcano.
    • Detected through shallow earthquakes and gas measurements.
  • Pyroclastic Flows:
    • Superheated gases that flow down the volcano, often following landslides.
    • 1980 eruption of Mt. St. Helens caused significant ecological damage.
  • Hydrothermal Explosions:
    • When steam escapes, potentially creating craters without magma.
Volcanic Gases
  • Role of Gases: Provide energy for eruptions; dissolved gases escape as magma rises or erupts.
  • Types of Gases Measured:
    • Carbon dioxide (CO2)
    • Sulfur dioxide (SO2)
    • Hydrogen sulfide (H2S)
  • Detection:
    • Spectrometers, sampling and laboratory analyses.
    • Observing effects on vegetation and wildlife as indicators of gas emissions.
Hydrothermal Activity
  • Process: Water infiltrates the ground, heated by magma, and can result in hot springs or geysers.
  • Indications of Magma Presence: Thermal features like soil temperatures or surface alterations monitored through various methods:
    • Aerial observations
    • FLIR thermal imaging
    • Direct temperature measurements
Seismic Activity
  • Earthquake Generation:
    • Caused by moving magma that reduces density, leading to pressure release.
  • Measurement:
    • Seismometers detect ground vibrations; patterns indicate magma movement.
    • Volcanic tremors provide information on magma’s behavior.
  • Historic Patterns:
    • Before the 1980 eruption, numerous magnitude >3.5 earthquakes were recorded daily.
Ground Deformation
  • Shape Changes: Volcanoes may inflate (bulge) or deflate (sink) due to gas or magma presence.
  • Measurement Methods:
    • Tiltmeters track angle changes in the volcano.
    • GPS measurements determine shifts over time.
  • Case Study: Between March and May 1980, Mt. St. Helens exhibited significant bulging, leading to its catastrophic eruption.
Volcanic Alert Levels
  • Normal: Typical background activity.
  • Advisory: Elevated unrest; monitored closely.
  • Watch: Increased potential for eruptions, some minor activity may be occurring.
  • Warning: Hazardous eruption in progress or imminent, requiring immediate attention.