Activity is monitored using the technique of Volcanic Surveillance. Multiple areas of science are used in studying the behaviour of a volcano. Data from all disciplines are collected, analysed and cross-referenced, to help give an understanding of behaviour at the volcanoes and an insight to future eruptions.


Volcanic Surveillance is based on the assumption that movement of molten rock or magma beneath a volcano will occur before any eruption can start and this movement of magma is detectable using various methods. Volcanologists use many techniques to monitor an active volcano; some of the main techniques are:

  • Visual and CamerasThe cheapest way of monitoring a volcano is just by looking at it!
  • Seismic MonitoringSeismic monitoring is the most widely used of the 'holy trinity' of volcano monitoring methods – seismic, deformation and geochemistry. Worldwide, almost all monitored volcanoes have some kind of seismic monitoring system and it is usually the first technique applied when scientists begin to monitor a volcano.
  • Ground DeformationOne of the key techniques used in volcano surveillance is monitoring ground deformation.
  • ChemistryAs the molten material (magma) rises to shallow levels, gases are released and they rise to the surface.
  • GasWhen molten material (magma) moves into a volcano it gives off volcanic gas emissions, sulphur dioxide (SO2), carbon dioxide (CO2) and hydrogen sulphide (H2S) which are measured regularly at our volcanoes. There are several techniques which include measurement done from an aircraft and on the ground. The four primary techniques, two airborne and two ground-based are outlined below.
  • Crater LakesWhen volcanic craters cool down after major eruptions, they often fill with water to form crater lakes. Some are cool, just filled by rain water, while others are warm or hot and remain connected to the volcanic plumbing. The colour of crater lakes varies markedly according to the temperature and chemistry of the water, and the type and concentration of particles suspended within it.


  • No labels

GeoNet is a collaboration between the Earthquake Commission and GNS Science.

about | contact | privacy | disclaimer | mobile

GeoNet content is copyright GNS Science and is licensed under a Creative Commons Attribution 3.0 New Zealand License