Volcanic Predictions

Volcanic eruptions don’t tend to just happen. There is usually some warning that a volcano will blow, and scientists will have an idea about what type of eruption will occur. The use of technology to monitor and study the volcanoes and their local environment also allows for improved modelling of volcanic hazards.

Monitoring a volcano
Volcanic monitoring (USGS, accessed 21/4/2020)
As you can imagine, one of the main events happening before a volcano erupts is that magma starts to rise towards the surface. This can lead to many changes in the volcano:
  • Surface temperature increase – this can be monitored using infrared (thermal) imaging cameras, usually from satellites.
  • Volume increase, or changing composition, of the gas released at vents – cameras can record this, and volcanologists take gas samples and analyse their chemistry.
  •  Bulges and changes in the shape of the volcano – tiltmeters and GPS satellites are accurate to within a few millimetres.
  •  Earthquakes or seismic swarms – as the magma and ground starts to move this causes small earthquakes. These are monitored with sensitive seismometers (which can even record footsteps of people walking nearby). Scientists look for changes from normal background readings.

 For more detailed information on monitoring find at more about the USGS Volcano Hazards Program

Volcanic Hazards
Lava bomb (Wikipedia Commons, accessed 21/4/2020)
  • Lava flow – although most lava flows are slow and can easily be out walked, there is little that can be done to stop them if your house is in the path of the flow.
  • Ash and tephra – volcanic bombs can be ejected at speeds of up to 400 km/per second and travel up to five km from the vent.  However, ash is the much more serious hazard. Not only can it completely cover cities (like Pompeii), it can reach high into the stratosphere and spread around the globe causing havoc for air travel and in some instance leading to lowering of global temperatures by partially blocking out some sunlight.
  •  Lahars – a violent mud flow where the material from a volcano mixes with water (usually from a river). This can become worse if there is snow or ice on the top of a volcano, which melts during the eruption, leading to an increase in water volumes in the river channel or valley. Lahars can flow at incredibly high speeds and have a huge amount of energy.  They are extremely dangerous.
  • Volcanic gases – these can be a silent killer.  They can spread out from a volcano with no visual or audible sign as was the case in the Lake Nyos Disaster, Cameroon.

Hazard maps and preparedness
The good thing about volcanoes is that the more they are studied, the better they are understood and the more certainly their hazards can be predicted. They are also relatively predictable. A stratovolcano is most likely to have an explosive eruption, ejecting ash and tephra, often causing lahars. Whereas a shield volcano will more likely have an effusive eruption with lava flows.  
Find out more in our Blow or Flow blog post
The eruption history of a volcano can also aide in making predictions about future eruptions. For example, if a volcano has been erupting regularly every 50 – 100 years, it is likely that it will continue doing so, and probably with the same behaviour. Mapping out the extent of previous lava and tephra flows will help forecast what might happen in future eruptions. Studying the contours of a volcano, particularly where the rivers and valleys are, can be especially important when considering where a lava or lahar flow may travel. Analysing average wind speed and direction for an area is also vital to assess where tephra is likely to fall. Scientists compile all this information to create hazard maps and to inform the local public and government if and where there is potential danger.
Mount_Adam_Volcanic_hazard_zones (USGS, accessed 21/4/2020)
Although we cannot stop a volcano from erupting, the research and observations being conducted help us prepare for and mitigate against the risks and hazards associated with them.
  • Have a go at creating your own 3D volcano and analyse possible paths of lahars or lava flows, by following this simple tutorial.
  • For a more in depth study of volcanic hazards and mitigation techniques, have a go at the WASP STEM Volcanic Hazards project. To assist you in examining the impact of slope angle on lava flow rates check out this video.