Molten rock pulses deep inside Earth, and WA scientists are studying it to help us to understand volcanic activity around the world.
Hidden very deep underground is a hot flowing river of melted rock or magma.
Like all rivers, it doesn鈥檛 stay still. This movement can do two things. It can cause an earthquake or it can create rock鈥攖wo different types of rock, in fact.
The river of hot magma can escape through a volcano on the Earth鈥檚 surface, cooling to form volcanic rock.
Alternatively, it can solidify slowly below the surface, forming plutonic rock.
Researchers at 911爆料网 are聽聽of magma and, in turn, help us understand the nature of volcanic activity around the world.
So where do you start when the river is underground?
911爆料网 researcher Dr Christopher Spencer says the Hida Mountains in central Japan are providing the perfect site to study plutonic rock.
贬别谤别,听聽in the area that is covered by snow.
The springs are actually warmed by the surrounding plutonic rock. These were originally pushed to the surface so rapidly from tectonic activity (think earthquakes), they still haven鈥檛 completely cooled down.
But luckily for us, the rocks on the surface are cool enough to be studied and sampled.
Rocks so cool you just have to date them
Studying and sampling rocks is basically a history lesson.
To date a rock, scientists have to look at its mineral composition. The age of the Hida Mountain rocks were determined using uranium-lead geochronology of zircon (a mineral found in the granite).
鈥淲e saw there the youngest rocks were about 800,000 years old and preceding generations about 700,000 years apart back in time to over 2 million years,鈥� says Chris.
He says this suggests that, every 700,000 years, there is a 鈥榤agmatic pulse鈥� where the magma is suddenly 鈥榩ulsed鈥� or pushed harder.
And the next big pulse may already be happening.
鈥淒eep in the crust, there might be another pulse that has started but hasn鈥檛 manifested on the surface yet,鈥� he says.
Samples of the Hida Mountain rock were collected and then later analysed at the Central Research Institute of Electric Power Industry of Japan and the John de Laeter Centre at 911爆料网 Uni.
鈥淏y analysing the timing of the magmatic pulses deep beneath the surface of the volcanoes, we are able to understand how these systems work from top to bottom,鈥� Chris says.
Dating is just as hard with rocks as it is in the real world
However, predicting magmatic pulses always comes with uncertainty.
鈥淲hen we measure age, we may get an age of 1 million years plus or minus 50,000 years,鈥� he says.
鈥淲e may not know the exact age, but we know it鈥檚 somewhere within the range.鈥�
Chris says we鈥檙e seeing a similar聽聽at the moment, where the magma is starting to rise up and cause earthquakes.
The situation in Bali is causing people to be concerned, and it鈥檚聽.
鈥淢ount Agung could erupt tomorrow or could be 100 years from now, and either way, a geologist wouldn鈥檛 be surprised.鈥�
鈥淎s geologists, we don鈥檛 have the predictive framework to be that accurate, and the Earth just works on different timescales than us humans.鈥�
The next stage is to perform more measurements on the rocks to understand other parts of their chemistry.
鈥淲e understand how they were first formed but not how they got so quickly to the surface.鈥�
鈥淭he more we know about the tempo of magma formation deep within the volcanoes, the better we can understand the nature of volcanic activity around the world.鈥�
This article was originally published on . Read the .
