Lecture 4 - Volcanic Hazard monitoring Flashcards
Short-term forecasting and monitoring
- Volcano monitoring in real time
- Eruption forecasting and prediction
- Volcano emergency management and planning
Long-term forecasting and monitoring
- Identification of high-risk volcanoes
- Mapping and identifying past volcanic hazards
- Long-term forecasts
Methods of volcano activity and eruption forecasting
- Seismic monitoring
- Ground deformation
- microgravity
- magnetic field
- volcanic gases
- temp
-hydrology
What causes volcano seismicity
When magma and volcano gases and fluid move it causes rock to break and vibrate,
Breaking = high-frequency earthquakes
Cracking = low-frequency earthquakes
How is seismic monitoring done?
Seismometers measuring timing, depth, location and magnitude of the tremors.
What do tremors of short period and harmonic tremors show?
Short period = fractures due to intrusion of expansion of magma chamber
Harmonic = Magma flowing
What is ground deformation?
Changes to the surface of the volcano due to processes below the surface.
Inflation - Gradual and can occur over months or years
Deflation - Sudden as the magma chamber is emptied
What are some ground deformation techniques?
Geodetic leveling - measures elevation change by knowing benchmarks in repeated surveys
cGPS - uses GPS and is very accurate
Tiltmeter - displacements as little as 1-2cm can be detected.
What is volcano gas monitoring?
Direct measurement of samples on the ground.
Airborne measuremnts of eruption plumes.
What could volcanic gas indicate?
CO2 is first gas to exsolve from magma, so increased CO2/SO2 ratio may indicate arrival of new batch of magma.
Sudden increase in SO2 may indicate eruption.
Temperature/Thermal monitoring
Detecting and analyzing active areas of a volcano.
Differentiate hot from cold eruptive events.
2 Stages of Hazard map production
- Documentation of previous eruptions
- Production of a hazard map to help identify threats from the volcano
