Radiometric method for dating volcanic deposits
A sample might be made up of different layers of ash (tephra), igneous rock and sedimentary rock, and there might be fossils or other material buried in the layers that offer further clues.As magma rises through the crust towards the Earth’s surface, it can cause the crust to move and bulge.With the combined information, volcanologists can start to develop an explanation.The clues give information about when a volcano erupted, what type of eruption it was and how much material was produced.As different events happen – volcanic eruptions, rain or sediments settling – layers of different rock can accumulate.Geologists can use this to tell more about when things happened and to date different events.
Each section of the core sample is recorded and numbered so scientists can reconstruct the layers in the right back in the laboratory.
Sometimes the rock the volcanologist is interested isn’t exposed, so they may need to drill deeper for samples.
Hollow steel pipes, 2 metres long, are driven into the ground using large weights.
This movement or deformation can be detected by using seismographs, which measure the Earth’s movement, so they are an important tool for studying whether a volcano might erupt in the near future.
If volcanologists suspect that a volcano is active or may be about to erupt, they can monitor the gases that are being released from the vent.
As magma rises from the field under the city, scientists may be able to see the bulges that are created in the Earth’s surface.