Volcano carbon dating
Sometimes the rock the volcanologist is interested isn’t exposed, so they may need to drill deeper for samples.
One problem is that basalt rocks (the type commonly found in Auckland) are generally very low in potassium, so this technique is not always reliable.
Radiocarbon dating can also be used to date the layers either side of the volcanic rock, such as sedimentary material that contains organic deposits.
Potassium-argon (K-Ar) dating is based on the same principle as carbon decay and can be used to date rocks directly.
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.
Back in the laboratory, an electron microprobe allows scientists to measure the composition of small rock fragments that have been collected in the field – what minerals and crystals are present and how old they are.