Predicting Volcanoes Flashcards
How does they use networked of siezmometers?
Typical warning signs that a volcano will erupt are increased earthquake activity, increased emissions of co2 and sulphur dioxide erases, ground deformation
Warnings are given to people in high risk areas
Earthquake activities beneath a volcano usually increases before eruption because magma and gases force their way up through the ground
Usually 4- 8 siezmometers are placed within 20 km of the event and volcano itself
Most volcanoes related earthquakes are magnitude 3 or less and occur within less than 10km of volcanoe
The earthquakes tend to occur in swarms consisting of dozens or hundreds
How does ground deformation indicate an eruption?
When rising magma forces its way through the ground the ground will usually tilt away from the centre of uplift
As the magma sinks back to the magma chamber the ground will tilt sword the centre of subsidence
Electronic tiltimeters continually record such ground tilts on volcanoes
Radar images from satellites are also used to detect ground deformation over larger areas
When volcanoes is close to erupting the speed of the ground deformation increases
How does has analysis indicate an eruption ?
The rate at which a volcano releases gases into the air is related to the volume of magma in the magma chamber
By measuring changes in emition rates especially key gases such as suffer dioxide and carbon dioxide, scientists can work out when a volcano will most likely erupt
Direct sampling of gas requires scientists directly enter a fumarole
Automatic chemical sensors send measurements by radio to volcanoes observatories
The remote location of these sites the hazardous fumes, frequent bad weather make regular gas sampling dangerous and sometimes impossible
