Our Treasures: Seismometer installed at Kiwi North


An earthquake in Fiji on May 24 was registered on Kiwi North’s seismometer. Photo / supplied

I can move things, but you can’t see me.

I can be measured on a scale, but I weigh nothing.

I am caused by faults, but no one has done anything wrong.

I am of course talking about an earthquake.

Once commonly referred to as The Shaky Isles, New Zealand is no stranger to an earthquake and most of us have a story or two about a time the earth moved us.

According to GeoNet, there are on average 20,000 earthquakes a year in our country, but only about 250 are big enough to be felt.

This is why I was so excited to see our newest treasure being installed at Kiwi North – a seismometer, which is an instrument that measures Earth’s shaking.

Our seismometer is a TC-1 model, built from a simple design that introduces several concepts from physics and engineering. It is made up of four key features.

A spring with a magnet attached that moves when the ground shakes, the moving magnet creates an induced current in a coil, an Arduino Uno micro-controller then receives that current and converts the analogue signal into a digital one, and finally, the digital signal is sent to a computer screen.

The seismometer here is one of more than 30 public units in schools and museums nationwide. This is an initiative by Rapid Characterisation of Earthquake and Tsunami (R-CET) and led by Geological and Nuclear Sciences (GNS).

Kiwi North's seismometer is a TC-1 model like the one pictured here. Photo / Supplied
Kiwi North’s seismometer is a TC-1 model like the one pictured here. Photo / Supplied

The network of seismometers is called Rū, named after Rūaumoko, the Maori god of earthquakes and volcanoes.

Four of these seismometers are operating in Northland, with more to be installed soon.

Dr Sophia Tsang, science to practice lead for GNS Science, explained that the physical shape of Northland makes it ideal for picking up data from across the South Pacific. Our own seismometer here at the museum even registered a May 24 Fiji earthquake, which, although it measured 6.3 on the Richter scale, was centred nearly 600km below the ground and didn’t create any surface waves.

An explanation of how the Rū setup works. Photo / Supplied
An explanation of how the Rū setup works. Photo / Supplied

Other notable events that have been recorded include an earthquake in Alaska last year that was picked up by a seismometer at Whangārei Girls’ High School, and several units around New Zealand registered the sonic boom from the volcanic eruption in Tonga in January.

These public units are designed for educational purposes, to inspire and generate interest in seismology, and the Rū here at Kiwi North continues to be a source of great interest for visiting kids and adults alike.

Mel Williams, visitor experience, Kiwi North



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