vulcanicity 2
- Created by: Sharon
- Created on: 29-12-15 12:45
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- Vulcanicity (2)
- Long term forecasting
- Geological history eg type of hazard and frequency by radiometric age dating.
- Once assessment made forecast what areas affected and how affected.
- this info combined with knowledge frequency and current surface, make volcanic hazard maps-plan evacuation,rescue and recovery.
- Short term
- Earthquakes- as magma moves to surface fractures rock =earthquakes. more earthquakes=volcanoe eruption
- Ground deformation- structure inflates as magma enters (tilt metres)
- Change heat flow- as magma rises water temp increases (infared)
- Change gas composition- prior to eruption increase in HCL & SO2.
- Primary effects
- Lava flows- strombolian and hawaiin eruptions, slow and people time - can destroy anything
- Pyroclastic flows- cause death by suffocation and burning few can escape.
- Ash falls- twice density of snow dont melt, can collapse roofs. far from eruption, kill vegetation therefore livestock - years after
- Gases- predominant is H20. others- HCL,H2S, HF,CO2. Sulphur along side ash reflect radiation back to space=cooling few years at most.
- Secondary & Tertiary
- Mudflows (lahars)- water and loose ash. hot or cold, high velocity.
- Avalanches & landslides- over steepened slows become unstable not necessarily due to eruption
- Flooding- drainage blocked by pyro and lava flows, melting of snow.
- avalanche, landslide, pyro, entering eater = tsunami
- Earthquakes- accompany eruptions as break through litosphere.
- WHY LIVE THERE???
- New land
- Fertile soil
- Mineral resource
- Industrial products
- Spas
- Tourism
- Long term forecasting
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