Today some DEVORA researchers (including myself) were filmed doing some fieldwork at some volcanic craters in Puhinui Reserve, near the Auckland airport. The craters were unrecognised as volcanoes until 2011, when researchers from Geomarine Research revealed their true nature. The objective of our fieldwork was to learn a little more about them. You can watch the piece, which aired on ONE News on Sunday, 28 April, here.
This study today was only a small part of a larger study on base surges in the Auckland field. When magma comes into contact with water, it results in a powerful explosion, which may create a base surge. Base surges are very fast-moving (around 100 m/s, or 360 km/hr), hot clouds of gas and ash that expand away, along the ground, in every direction from the explosion site. They leave tell-tale deposits behind that we can study. Interestingly, there is evidence for base surges on Mars.
Auckland is quite a wet place–we are surrounded by the sea, and we also have lakes and a lot of groundwater. So it makes sense that we see evidence that a majority of the 53 volcanoes in the Auckland Volcanic Field started with explosive base surges created when magma came into contact with water. Darren Gravley and his team at University of Canterbury are using Ground Penetrating Radar (or “GPR”) to study base surge deposits from several AVF volcanoes of different sizes. They want to figure out how far and fast the base surges traveled, partly to understand how large of an area to evacuate before an eruption. The information may also be used to model the impact of future base surges on Auckland buildings.
I’ll let some pictures tell the story from today (credit: Cheng Yii Sim):
I want to thank Science Media Centre NZ, particularly the Science Media SAVVY course leaders, TVNZ’s Will Hine, fantastic camera man Bruce, and our research team for making it a great day for science and science outreach:
Simon Aiken (he’s first on this link’s list)