Sunday, November 21, 2021

Highland earthquake was 'quite unusual', says expert

The earthquake which hit Scotland was "quite unusual" because people could actually feel it, a seismologist said.

By Alison Campsie
Saturday, 20th November 2021, 
The earthquake was felt in Roybridge, Lochaber, on Friday. PIC: Jim Barton/geograph.org.

The British Geological Survey (BGS) reported a 2.2 magnitude earthquake just outside Roybridge, near Spean Bridge, in the Highlands on Friday around 9.30pm.

It was the second quake to hit the country in less than a week.


The earthquake, which had a depth of 7.5km, was described by Glenn Ford, the BGS seismic analyst on call at the time of the tremor, as "absolutely tiny" when compared with other quakes seen around the world.

But he said this one was unusual as only around 10% of earthquakes are felt at all.

Mr Ford said: “In UK terms, because we are a very low seismic area, we only perhaps get about 15 earthquakes a year of this size or greater, so it's quite unusual in that respect.

"We get about two to three hundred earthquakes every year somewhere in the United Kingdom area, so the fact that this one was actually felt was unusual because approximately 90% of them are so small nobody actually perceives them."

One person who did feel it was Iain MacDonald, who was staying in the village at the time of the tremor.


He said: "It was about 9.30pm and I felt the tremor, but I heard it much more. It was really quite loud, like a train rumbling past the house.

"To me it seemed like a train rumbling past. I knew what it was straight away, I have heard it before and felt the tremor before."

The quakes was 17 billion times smaller than the earthquake which devastated Japan in 2011, said Mr Ford.

He added: "You literally wouldn't look up from your coffee or your newspaper for an earthquake that size in California or Japan."

He added there were a number of factors as to why people felt earthquakes in the UK, including size and depth.

"The other type is time of day. Because people are not used to earthquakes in the UK, they put a small earthquake, because it could just be a small tremor, down to traffic noise, so if somebody is in a very remote area like this which occurred last night there is much better opportunity to actually feel it because they are nice and still, it was late at night, and probably in a sedentary position," Mr Ford said.

"Normally if the roads had been busy or you're near a motorway, you'd just put it down to traffic,” he added.

A 3.1 magnitude earthquake was reported by the United States Geological Survey (USGS) on Tuesday just before 2am, with its epicentre some 11 miles north-west of of Lochgilphead, 88 miles north-west of Glasgow.

More than 30 people reported to the USGS that they had felt the tremor, with reports coming from as far as Edinburgh and Ballycastle in Northern Ireland.

The agency said that quake happened 10km below the Earth's surface.

As for the recent quakes in Scotland, Mr Ford said there had "obviously been a little bit of stress built up in that area".

Data from the British Geological Survey shows between 200 and 300 earthquakes are detected in the UK every year, with tremors of between 3.0 and 3.9 magnitude occurring on the mainland once every three years on average.

Earthquake Scotland: Reports of tremors of west Scotland earthquake coming from as far as Edinburgh and Northern Ireland

Residents of western Scotland received a bump in the night after an earthquake shook the region in the early hours of Tuesday.

By Trevor Marshallsea
Tuesday, 16th November 2021

A quake with a magnitude of 3.1 occurred just before 2am with its epicentre some 11 miles north-west of the town of Lochgilphead, 88 miles north-west of Glasgow, the United States Geological Survey (USGS) said.

More than 50 people reported to the USGS that they had felt the tremor, with reports coming from as far as Edinburgh and Ballycastle in Northern Ireland.

The agency said the quake happened 10km below the Earth's surface.

Data from the British Geological Survey shows between 200 and 300 earthquakes are detected in the UK every year, with tremors of between 3.0 and 3.9 magnitude occurring on the mainland once every three years on average.

In August of 2017, Scotland experienced its biggest earthquake in years, which had a magnitude of 4.1. It occurred in Moidart, but was felt widely across the northwest of Scotland.

The epicentre of the earthquake was located some 11 miles north-west of the town of Lochgilphead, however, tremors were felt as far as Edinburgh and Ballycastle, North Ireland.




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