Volcanoes - OCRMonitoring volcanoes - popular techniques
Composite and shield volcanoes are found along plate margins. They have distinctive characteristics and can have both positive and negative effects on people and the landscape.
Volcanic eruptions are unpredictable, so volcanoes can be monitored to estimate when and where they are likely to erupt. A variety of techniques are used:
seismometerA machine that detects seismic waves caused by earthquakes. - measure the seismic waves occurring before and during an eruption
tiltmeterA device that measures any changes in the 'tilt' of the landscape. It is used often for studying volcanoes., GPS satellites and lasers - monitor any changes in landscape, since volcanoes tend to swell near an eruption
'spider' robots - monitor gases escaping from a volcano, as there is often an increased release of sulphur dioxide near an eruption
thermometers - measure temperature as volcanoes become hotter when magma starts to rise through the main ventThe thin narrow pipe in the middle of a volcano that connects the magma chamber to the crater.
chemical analysis of water in local rivers and lakes near volcanoes - as volcanoes release minerals which seep into the surface and ground water before and during an eruption
data analysis - by looking at the past history of eruptions to identify patterns of activity