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Tag Archive: British Geological Survey


More sinkholes open up in Britain

Several cars that collapsed into a sinkhole in Bowling Green, Kentucky, in February 2014. Photo / National Corvette Museum/AP

Several cars that collapsed into a sinkhole in Bowling Green, Kentucky, in February 2014. Photo / National Corvette Museum/AP

A spate of sinkholes have opened up across the country as floodwater dissolves the underlying rock, while a “second wave” is likely to appear in the coming weeks as the rain stops and the ground begins to dry, the British Geological Survey warned yesterday.

The number of sinkholes reported has soared to six so far this month – many times more than the one to two that is typical across the whole of a normal year, experts said.

These have generally occurred as soluble rocks such as chalk, limestone and gypsum have been eroded by a sudden infusion of water from the heavy rainstorms which has made existing underground cavities bigger and causing the ground above it to collapse.

Read more:Sinkholes: What are they, how do they form and why are we seeing so many?

A house collapsed in Ripon this week when a sinkhole appeared following the erosion of the underlying gypsum.

This followed a particularly large 20ft deep sinkhole in a Hemel Hempstead garden on Saturday which forced the evacuation of about 20 homes.

“There has been a significant increase in sinkholes over the past few weeks and it’s reasonable to suggest that this is related to the increase in rainfall,” said Dr Vanessa Bank, of the British Geological Survey.

“How long this goes on for very much depends on the weather. But there is likely to be more rainfall and my personal opinion is that we are talking about weeks,” she added.

 

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GlobalResearchReport.com

On Saturday, a huge sinkhole opened up at the side of a house in Hemel Hempstead, Hertfordshire. Swallowing up half of the front lawn, it was 35ft wide and 20ft deep.

Last week, a hole as deep as a double-decker bus is high suddenly opened up in the back-garden of a house in South-East London, almost swallowing a child’s trampoline as the ground collapsed without warning.

Had the poor owner’s daughter been rushing out to play on the trampoline, she could have very easily have been seriously injured or even killed.

 25' Sinkhole Opens Up On Yorkshire Street

Dangerous: A 50ft-deep hole appeared in the central reservation on a section of the M2 in north Kent last week

Two weeks ago, there was a similarly narrow escape for a family living in High Wycombe, when, overnight, a deep hole appeared  without warning in the driveway just next to the house.

This time the adult daughter’s car did end up buried at the bottom of the hole, thankfully, while there was no one in it.

And in Kent last week, motorists hoping to use the M2 were left fuming by the motorway’s temporary closure, after a substantial hole — 15ft deep — suddenly appeared in the central reservation. Again, no one was hurt but had the hole opened up just a few yards away, it is obvious what a different story it could so easily have been.

All of these holes are what the public call sinkholes and now, after weeks of heavy rain, they seem to be appearing with ever greater regularity. Hard statistics are difficult to find — not least because sinkholes that appear on farmland often go unreported — but having studied them for 35 years, I’d estimate that sinkholes are currently appearing at four-to-five times their normal rate.

 
Gone: A Volkswagen Lupo was swallowed up by this sink hole in High Wycombe, Buckinghamshire

Gone: A Volkswagen Lupo was swallowed up by this sink hole in High Wycombe, Buckinghamshire

Brand new: Zoe Smith, 19, was given a replacement after the car was engulfed by the hole which developed outside her home

Brand new: Zoe Smith, 19, was given a replacement after the car was engulfed by the hole which developed outside her home

 

With more heavy rain forecast, I’d be surprised if we’ve seen the last sudden sinkhole of this winter.

Even when the rain does stop and warmer weather returns, for reasons that I’ll come to, there could be a second spate of them.

Strictly speaking — and as I work for the British Geological Survey I do need to be strict about these things — not all the big holes that have been appearing are sinkholes. Technically, a sinkhole is a hole that opens up when the surface layers collapse into a naturally made cavity. When the surface layers collapse into a cavity made by man  — and at least two of the recent holes are in areas where mining has been carried out in the past — then it should be called a dene or crown hole.

But given that both types are caused by a collapse into an underground cavity and the end result — a large, potentially dangerous hole in the ground at the surface — is the same, for the sake of simplicity, let us call them all sinkholes.

Certainly, anyone suffering the tragedy of having their house fall into one won’t be worrying about the difference. Fatalities caused by sinkholes in this country are thankfully very rare, but a homeowner in Florida did die in exactly those circumstances only last year.

Risk: Gretel Davidson feared she would have to pay around £10,000 after a sinkhole twice the height of a double-decker bus appeared in her garden in Banehurst, South-East London

Risk: Gretel Davidson feared she would have to pay around £10,000 after a sinkhole twice the height of a double-decker bus appeared in her garden in Banehurst, South-East London

The sheer size of sinkholes and their sudden appearance without warning does make them extremely hazardous. This explains why in  the superstitious distant past,  their appearance was often linked to misfortune.

Some saw them as a direct route to Hell itself; one near Darlington that collapsed in the 12th century  is called Hell Kettle and the  rising groundwater in it steams in the winter.

Of course, it’s not the Devil but all the heavy rain that lies behind the sudden spate of sinkholes. Rainwater dissolves limestone easily because it gets acidified from  carbon dioxide in the air and by  passing through rotting vegetation or certain types of rock.

The water dissolves rocks such  as chalk, limestone and gypsum, making existing natural underground cavities bigger. It also scours fine material out of existing cavities. In addition, it makes the surface layers of soil composed of such things as clay or gravel heavier as they become waterlogged.

Bit by bit, the cavity becomes a little bigger, the covering layers a little heavier until . . . snap . . . those covering layers no longer have the mechanical strength to span the cavity and suddenly they collapse into it, taking anything unfortunate to have been standing on the surface down with them.

Concern: A 35ft wide hole appeared underneath a home in Hemel Hempstead last week, prompting the surrounding properties to be evacuated

Concern: A 35ft wide hole appeared underneath a home in Hemel Hempstead last week, prompting the surrounding properties to be evacuated

It’s no accident that sinkholes often seem to appear next to a fairly substantial piece of civil engineering, such as a house or road, rather than underneath the piece of civil engineering itself.

As long as we put roofs on houses and impermeable cambers on our roads, rainwater will be thrown off the things being protected. It’s often where that rainwater ends up — by the side of the road, by side  of the house — that becomes  vulnerable to sinkholes.

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Earth Watch Report – Volcanic Activity

University Of Bristol

Press release issued 18 January 2013

Details of around 2,000 major volcanic eruptions which occurred over the last 1.8 million years have been made available in a new open access database, complied by scientists at the University of Bristol with colleagues from the UK, US, Colombia and Japan.

Volcanic eruptions have the potential to cause loss of life, disrupt air traffic, impact climate, and significantly alter the surrounding landscape.  Knowledge of the past behaviours of volcanoes is key to producing risk assessments of the hazards of modern explosive events.

The open access database of Large Magnitude Explosive Eruptions (LaMEVE) will provide this crucial information to researchers, civil authorities and the general public alike.

Compiled by an international team headed by Dr Sian Crosweller from the Bristol’s School of Earth Sciences with support from the British Geological Survey, the LaMEVE database provides – for the first time – rapid, searchable access to the breadth of information available for large volcanic events of magnitude 4 or greater with a quantitative data quality score.

Dr Crosweller said: “Magnitude 4 or greater eruptions – such as Vesuvius in 79AD, Krakatoa in 1883 and Mount St Helens in 1980 – are typically responsible for the most loss of life in the historical period.  The database’s restriction to eruptions of this size puts the emphasis on events whose low frequency and large hazard footprint mean preparation and response are often poor.”

Currently, data fields include: magnitude, Volcanic Explosivity Index (VEI), deposit volumes, eruption dates, and rock type; such parameters constituting the mainstay for description of eruptive activity.

Planned expansion of LaMEVE will include the principal volcanic hazards (such as pyroclastic flows, tephra fall, lahars, debris avalanches, ballistics), and vulnerability (for example, population figures, building type) – details of value to those involved in research and decisions relating to risk.

 

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