Earth-shattering experience in Burren

WHEN you think of earthquakes and all things seismological, Ireland is probably not the first place that comes up on your Richter Scale.

Our little island does not feature on any major fault line, does not spew hot ash and lava from active volcanoes and the worst recorded earthquake felt here was a 5.4 in 1984. The epicentre of that particular shudder was in fact in Wales but was felt all along the east coast of Ireland.

“I was still in bed when I felt it,” recalls Tom Blake, director of the Irish Seismic Network.

“It was at three minutes to eight in the morning; a very calm, very blue sky morning. I was newly married at the time and I was doing research in here so I had to rush in here when it happened. The phones were alight. It was felt as far inland as Portlaoise. Significantly it was only 20kms below the surface. In Ireland you’d normally expect to get between magnitudes 1.5 to 2.5.”

The network has operated from its headquarters in Merrion Square, Dublin since 1978. Irish involvement in seismology goes back much further however. The aptly named Dubliner, Robert Mallet, is known as the father of seismology and is well-known in the field for his pioneering work.

“Mallet was the first person to say that earthquakes were not wrath from god or that they’re not due to a shrinking earth,” says Blake.

“He said that there had to be a purely physical explanation for this; it’s a build-up of stress. He ran experiments in 1840s and 50s on Killiney beach where he detonated explosives to show how the energy from an earthquake changes as it goes through different layers of rock.”

As well as being credited with coining the terms seismology and epicentre, Mallet delivered countless papers and lectures on the subject. In keeping the spirit of Mallet alive, a big part of the network’s work is education. In the last five years it has helped install seismometers into 55 schools across the country.

“Schools would ring me up and invite me to give lectures to them and it became so popular that we decided to do something concrete,” says Blake pointing at a simple looking contraption in a glass case.

“Around about that time this seismometer became available at a very reasonable rate that schools could afford,” he says.

The seismometer itself looks like a mixture of very a small spinning machine and an elaborate clothes hanger. Each one costs €750 but for Blake its educational value is boundless.

“Students immediately have to start talking about frequency, amplitude and wavelength in relation to describing earthquakes and it automatically gives them a label on which they can hang the theory they learn in maths and physics,” says Blake.

“So they need to use this vocabulary to describe what they see on the screen. And when they see that the words they use in maths and physics have a meaning in their everyday life, well then of course it takes on a whole new meaning. In the new Physics Leaving Cert Honours syllabus there’s a whole section dedicated to earthquakes. So hopefully we’ll see that passed and it will mean students are learning about seismology from an early age,” he says.

The readings taken from the seismometers across the country are not limited to those shakes we get in Ireland of course. Like all seismometers across the globe, the recently installed seismometer at the Cliffs of Moher Interpretive Centre has picked up waves from as far away as New Zealand, Indonesia and Japan. On the day we visit the centre the screen is a sea of red flashing dots from all across the world.

“The other day we had really good readings of the earthquake in Guatemala,” says Katherine Webster referring to the magnitude 6.2 earthquake that happened in Guatemala City last Monday. “That came through very quickly because the waves were travelling a much shorter distance than some of the other ones you can see from further away. The waves were much larger than some of the ones from further afield.”

Funded by the Geological Survey of Ireland, the seismometer at the famous cliffs was connected back in February 2012.

“The Cliffs of Moher are part of the Cliffs of Moher and Burren GeoPark which is a UNESCO recognised designation received in October 2011,” says Webster.

“The whole concept of geological heritage is a factor for tourists; both educational groups and main stream tourists who just have an interest in earth sciences and so on.

“There are all sorts of geological trails and attractions with a geological angle being set up at the moment, so this really ties us in with that whole world of seismology and in turn that geological ethos.

“We’re absolutely delighted to have the seismometer here and it really adds to the whole experience. There’s a huge interest among tourists in the information that they’re seeing there. It really adds to the overall experience.”

One of the most recent earthquakes recorded in Ireland was in Clare in 2010.

“I think it was a 2.7,” he says. “I actually remember I was sitting up in bed reading a book and I thought my neighbour was moving furniture or something around because I heard what I thought was a big wardrobe or something falling over.

“There was a bit of a shake I seem to remember but there certainly was quite a loud noise. It wasn’t until the following morning that I actually realised that it had been an actual earthquake.”

“It was all over the local radio that morning and certainly everyone was talking about it in work. We got some phone calls from the media to see had there been any impact on the cliffs themselves but there was nothing that we could observe, nothing discernible.”

According to Blake, Ireland should not be complacent however. A large fault line in the mid- Atlantic ridge has affected the country before.

“We’ve got to be careful,” he says. “On November 1, 1755 there was an earthquake and tsunami recorded in Lisbon. And it’s reported in the Cork Journal of November 2 that 15ft waves were experienced as a result of that tsunami. The actual shuddering of that earthquake was also felt as well on the south coast. A side-effect of that is Barleycove; the sand is all displaced there as a result of that tsunami.”



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