1. Volcanic Hazards

5. Volcano Explosivity Index

7. 3. Eruption Type

8. Icelandic Eruption e.g. Eyjafjallajökull

9. Hawaiian e.g. Kilauea

10. Strombolian e.g. Stromboli

11. Vulcanian e.g. Sakurajima

12. Vesuvian e.g. Vesuivius

13. Peleean e.g. Sinabung Indonesia

14. Plinian e.g. Pinatubo

15. Geoff Mackley

17. Tephra Collective term for all airborne or groundflowing
pyroclasts including solidified magma.
Tephra is classified according to size:
Bombs: > 64mm diameter
Lapilli 2-6mm diameter
Ash <2mm diameter

18. Lava Shield – Low Viscosity (flows far)
Cone – high Viscosity (explosive, cools quickly)
Not usually a major hazard, flows in channels or is slow enough to move away from it
Pocaya – Guatemala
Kilauea – Hawaii

20. Lava Bomb
Molten rock, ranging in size from stones to house sized boulders. Explode out of cone volcanoes and can travel many miles
Mt Etna

21. Pyroclastic Flow
Superheated gas cloud cascades down the mountain at speeds of up to 450 miles per hour. Unzen Volcano Japan
Nuées Ardentes are similar to pyroclastic flows, but the main component is lava based (PF are more gas based). NA often glow

22. Ash
Ash causes many issues. It can destroy engines such as in aeroplanes due to its glass like structure.
It causes breathing difficulties, destroy crops and can collapse roofs
Eyjafjallajokull Iceland

23. Steam
Not usually a major hazard, but can cause ash to be propelled very high and travel greater distances

24. Gas Mainly CO2 and SO2. Toxic and can kill people, animals and plants
Gas may also lead to acid rain
Papandayan Volcano Indonesia

25. Lahar (Mudflow)
Ice from the top of a volcano (or heavy rain) mixes with ash to form a raging river of mud that can bury entire towns
Mt Merapi Indonesia
Nevado Del Ruiz

26. Frequency and Regularity?
Data covering the last 10,000 years
Historical records can give us a ‘x year cycle’ but the reality is that averages are just that. A 200 year volcano may not erupt for 400 years, the do so twice in a decade.

27. Prediction Volcanoes can be active, dormant or extinct.
They usually give warning signs before an eruption

28. Monitoring

29. Ground Deformation
Changes to the surface of a volcano (volcano deformation) can provide clues about what is happening deep below the surface. Most volcano deformation can only be detected and measured with precise surveying techniques. The Volcano Hazards Program has installed networks of sensitive deformation instruments around volcanoes to monitor changes over time. These instruments, along with satellite-based technologies help us to better understand the volcanoes we watch and allow us to provide eruption warnings.
GPS devices = Can measure change around 1cm
EDM (Electronic Distance Meter) = Infrared accurate 5mm
Tiltmeters = Spirit level on a stick = Accurate degrees

30. Remote Sensing InSAR (Interferometric Synthetic Aperture Radar)
Uses satellite technology
Can monitor en tire moutains

31. Gas
Scientists have long recognized that gases dissolved in magma provide the driving force of volcanic eruptions, but only recently have new techniques permitted routine measurement of different types of volcanic gases released into the atmosphere.
Gases released by most volcanoes are difficult to sample and measure on a regular basis, especially when a volcano becomes restless. Direct sampling of gas requires that scientists visit a hot fumarole or an active vent, usually high on a volcano's flank or within its summit crater. 
Some gases can be monitored remotely but weather and access mean that this is not always fully achievable

32. Seismicity
Moving magma triggers ground movement like a mini earthquake.
A seismometer is an instrument that measures ground vibrations caused by a variety of processes, primarily earthquakes. To keep track of a volcano’s changing earthquake activity, we typically must install between 4 and 8 seismometers within about 20 km of a volcano's vent, with several located on the volcano itself. Seismic networks are made up of several instruments.

33. Hydrology
Borehole and well hydrologic and hydraulic measurements are increasingly used to monitor changes in a volcanoes subsurface gas pressure and thermal regime. Increased gas pressure will make water levels rise and suddenly drop right before an eruption, and thermal focusing (increased local heat flow) can reduce or dry out acquifers.

34. Geo Physical
Measuring the temperatures using satellites, infra red technology
Or traditional thermometers using fumaroles and/or vents

36. Phreatic Eruption However, it is not a perfect science
Phreatic eruptions are steam-driven explosions that occur when water beneath the ground or on the surface is heated by magma, lava, hot rocks, or new volcanic deposits (for example, tephra and pyroclastic-flow deposits). The intense heat of such material (as high as 1,170° C for basaltic lava) may cause water to boil and flash to steam, thereby generating an explosion of steam, water, ash, blocks, and bombs.
These are very hard to predict and was the reason Mount Ontake in Japan resulted in 48 deaths