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What Lies Beneath?

Our thoughts about geology, geohazards, GIS, data and much more.


Latest Blogs

Chris Milne

12th June 2020

Coastal erosion – stopping your dream home becoming a nightmare

Maura Partridge

27th May 2020

Property Value Falls off Cliff

Tom Backhouse

20th May 2020

Isolation thoughts - Embrace the Chaos

Lucy Oxer

7th May 2020

The Government is at a Geospatially Located Crossroads

What we can Learn from the Open Release of Flood Data

In 2009 Berners-Lee suggested to Gordon Brown that the best way to make use of the internet was to put all the government data on it. To his surprise, Mr Brown said...

30th April 2020

Coal Workings Re-imagined: Variations in Coal Mining through Time

This post will cover year-on-year changes in mining depth using Terrafirma’s 25m resolution Working Depth Model (WDM), a point cloud of 33 million points representing all known...

23rd April 2020

A Coastal Cliff Hanger

Coastal Erosion. It’s been a hot topic in recent months due to the exceptional wave surges triggered by Storm Ciara and Storm Dennis. Red warnings were issued across the UK...

1st April 2020

Falling Tree gets to the Root of the Mining Problem in Cornwall

The uprooting of a tree following a recent storm has led to a significant ground collapse in Beacon, Camborne. The 10-metre-deep and several metre-wide sinkhole, located behind...

11th March 2020

Sinkhole at Wooburn Park - The Perils of Forgotten Mining

The 12-metre-deep ground collapse discovered in Sappers Field, Wooburn (near High Wycombe) on 29th February reveals a history of mining, hidden beneath the ground for over 150 years...

5th March 2020

Storms highlight uncertainty over ground hazard and risks

It has been a stormy few weeks, both meteorologically and politically. The damage during Storm Ciara included a sinkhole in Brentwood, which swallowed a car, and now political storms have blown up...

14th February 2020

New Year, New Landslip

As is often the case during the winter months, there has been a spate of large landslides along coastal parts of the UK. Norfolk has taken a significant hit with regards to slope failures in recent...

9th January 2020

2019: A Year in Review and Looking Towards 2020

2019 has been a year of change at Terrafirma; time and resources have been invested in our growing team and we have established a new GeoData Department, which will be a key area of focus in 2020...

18th December 2019

Ground Collapse as Wet Weather Sets in

Weather in the UK has been unsettled recently, and the cold, wet start to October has been no exception; Evy Hughes, Geologist at Terrafirma explores the latest sinkhole that appeared in Kent...

4th October 2019

Terrafirma Explore the Historical Mining Landscape of Cornwall

As lots of people were making their way back to reality from their summer holidays, a few members of the Terrafirma team made the journey down to Cornwall to explore the historical mining landscape...

25th September 2019

Unforeseen Effects of Climate Change on
Ground Stability

Subsidence is likely to increase if more extreme weather occurs due to future climate change, and unforeseen effects on a range of ground and property related issues. Recent dry summers in 2003, 2006 and...

5th September 2019

The Slippery Truth About Landslides

Those of us who followed this year’s Tour de France will still be reeling from the last-second upset to the competition: Julian Alaphilippe’s lead, which he had held for 11 consecutive days, suddenly ripped away...

31st July 2019

New Guidance Issued by Coal Authority

The Coal Authority (TCA) has issued new guidance TGN01/2019 on the potential effects of the collapse of deep pillar and stall working, based on events which occurred at a new housing development the Bayfield...

21st June 2019

Wet Weather Causes Ground Instability Across UK

The recent severe weather has the UK on course for what could be the wettest June on record. Torrential and persistent rain has been falling across the British Isles, with some villages experiencing 73mm of...

13th June 2019

Sinkhole Causes M25 to Close

On the evening of 10th June 2019, the M25 was closed between junction 5 and 4 following a road traffic collision and the discovery of two sinkholes in the central reservation. These sinkholes have...

11th June 2019

Coal and Brine - Take it with a Pinch of Salt

The UK has a vast coal mining legacy, with 385,000 buildings within 20m of a mine entry and nearly one in three properties falling into a coal mining reporting zone. A CON29M is required to be carried out...

5th June 2019

Disruption in Durham and Dorset

As summer’s around the corner, is the warmer weather to blame for the recent sinkholes in Durham and Dorset? Using specialist GIS software and geology knowledge, Tim explores why two separate sinkholes…

15th May 2019

St Alban's Sinkhole: Part 2

Terrafirma explore the possible causes of the recent St Albans sinkhole for a recent BBC3 radio interview. Early on the 6th November a sinkhole appeared adjacent to a block of flats in a residential area of...

12th November 2018

What is Radon and Does it Affect Your Property?

Radon is a naturally occurring, radioactive gas that forms from the decay of uranium within the ground. Owing to the way we often heat and ventilate our homes, radon can enter the house, causing exposure to...

7th November 2018

Environmental and Ground Hazards – Do You Always Need a Search?

A diligent property professional will always recommend undertaking searches for each transaction, so the purchaser can paint an accurate picture of any hazards and restrictions that may affect their future...

30th October 2018

Innovation in Cornish Property Risk Assessment

Cornish mining expert, Cornwall Consultants and national mining and ground report specialist, Terrafirma, have announced a collaboration that sees the launch of a new Ground Report combining leading digital...

12th October 2018

The Impact of Coal Mining

Explore the legacy the UK's once great coal mining industry has left on property and land in Terrafirma's new Infographic. With almost a third of all buildings in the UK underlain by coal mines, over 9,000...

24th September 2018

Introducing: The Ground Report

Terrafirma, an expert provider of environmental information and data intelligence, today launched the Ground Report, a risk and liabilities report designed to enable property professionals to better identify...

11th September 2018

Ripon: The UK's Sinkhole Capital

This week yet another sinkhole opened formed in an alley-way just off Ripon’s main high street as the Yorkshire town continues to live up to its name. The event led to the evacuation of a nearby supermarket...

24th August 2018

Terrafirma First Commercial Organisation Licensed to Produce CON29M Report

Terrafirma, an expert provider of environmental information and data intelligence, has become the first commercial organisation to be licensed by The Law Society as a ‘Report Producer’ of the official CON29M...

10th July 2018

Shaft Swallows Car Park in St. Ives, Cornwall

Late on Saturday 28th April, a 40ft deep and 3ft wide hole opened in a car park in Garth-An-Creet, St. Ives, Cornwall. Local emergency services were called to assess the scene and undertake work to prevent...

30th April 2018

West Wales Sinkhole Forces Closure of The A40

A sinkhole discovered at 6pm on Wednesday (18/04/2018) has appeared on the A40 near Llandovery in Carmarthenshire [1,2]. Police say the sinkhole has been treated but the road remains closed in both...

19th April 2018

Merthyr Tydfil Sinkhole Opens up on New Build Development

A sinkhole reported on 02/04/18 has appeared in Merthyr Tydfil within a new build site, Cwrt Aneurin Bevan. The sinkhole which is reportedly 20 ft (6m) deep has resulted in local residents losing access...

12th April 2018

Sinkhole Appears in Rugby Pitch in Swansea

A sinkhole which is said to have collapsed on the 14th February 2018 appeared in the corner of one of the Morriston RFC rugby pitches in Heol Gwernen, Cwmrhydyceirw. A report was received on Monday, 19th...

27th February 2018

February: A Month of Winter Sinkholes

Between the 14th-16th of February two sinkholes opened up in the City of Norwich, the second of which spanning over two front gardens in Meadowbrook Close. Although described by the water board as a...

27th February 2018

Analysis of the Harrington Sinkhole, Cumbria

On the 4th January 2018, a 1.2m deep, 0.6m wide ‘’sinkhole’’ opened next to the Whitehaven – Workington railway line, near the coastal village of Harrington in Cumbria. For fears of the hole expanding...

10th January 2018

2017: A Year in Review

As the year rapidly draws to a close, at Terrafirma, we thought we would summarise this amazing year, including providing a top 5 of our 'What Lies Beneath' blog and our key 2017 events. 2017 has been...

21st December 2017

SinkholeAlert: Demonstrating Disaster with Data

At Terrafirma, understanding the ground is what we do best: Our CEO Tom Backhouse was recently asked to feature in Channel 5’s documentary Sinkholes to provide an expert insight into the roots...

4th December 2017

Sinkholes: Explained

The word sinkhole has become a term broadly used term to describe any hole in the ground created by erosional processes and the drainage of water. Ground hazards in the UK are often synonymous with...

27th November 2017

Terrafirma CEO on Rip off Britain

Earlier today, Terrafirma's CEO and Founder, Tom Backhouse featured on the new series of the Rip Off Britain: Live Series on BBC One. Tom was invited on to offer advice to a frustrated home-owner who...

17th October 2017

The Hidden Ground Risks to Farmers and Landowners

Land. A word that is defined by its ownership, purpose, value or location and is often viewed, from a local, regional or national economic perspective, for its agricultural or development potential...

13th October 2017

Could the Wednesbury 'Sinkhole' have been Predicted?

The formation of a ‘sinkhole’ beneath a property in Wednesbury, West Midlands has received abundant coverage from the mainstream media during the last week. At Terrafirma, we have been looking into...

13th October 2017

Sinkhole in Brow Gate, Baildon

On September 25th, 2017, a large sinkhole appeared on the pavement at a pedestrian crossing in Brow Gate, Baildon, causing traffic disruption indefinitely. According to a pedestrian, the sinkhole...

26th September 2017

Neath Sinkhole Saga

A sinkhole has been reported to have occurred within part of Beechwood Avenue, Cimla in South Wales. This is the second reported sinkhole in the neighbourhood after another ground collapse, later...

19th September 2017

Protect Property with a Professional Opinion

The age of solely relying on data in environmental risk assessment is over, with a visible shift in the way professionals perceive risks such as contaminated land and flood. Where historically...

19th September 2017

Sinkhole Appears in High Street Green, Hemel Hempstead

On May 2017, an 8-metre-deep sinkhole appeared on High Street Green, Hemel Hempstead, causing the road to be closed until around November. This is in the same neighbourhood (within 200 metres...

25th August 2017

Sinkhole on Edge Lane, Liverpool

On 29th June 2017, a 6 metre wide and 3 metre deep sinkhole opened in the middle of a busy Liverpool commuter route to the M62, Edge Lane, closing it for several weeks. United Utilities were...

7th August 2017

Chalk Mine Collapse at Field Road, Reading, Berkshire

The collapse of a chalk mine in west Reading forced the immediate evacuation of dozens of residents. These residents then suffered for years due to the extensive and drawn out remediation of...

18th July 2017

Sinkhole at Pinner Wood School, Harrow, Greater London

A large sinkhole opened in the car park of Pinner Wood School, Harrow, forcing its immediate temporary closure. Geotechnical surveys and site investigations have been commissioned to determine...

12th July 2017

Coal Mining and the Need for Interpretive Analysis

A sinkhole has formed during September 2015 on Bull Street, Lower Gornal Dudley, West Midlands. As a physical example of ground subsidence, the Bull Street Sinkhole (BSS) is hardly remarkable...

13th June 2017

Sinkhole Appears as Mine Shaft Collapses in Scorrier, Cornwall

On the 14th March 2016, a 90 metre (300ft) deep mine shaft opened destroying the patio and a garage within a bungalow in Scorrier, near Redruth, Cornwall. Fortunately, the £200,000 property was...

15th March 2017

Most Recent of Long Legacy of Sinkholes Appears in Ripon

On the 9th November 2016 a naturally occurring sinkhole opened up on Magdalens Road near the River Ure in west Ripon. The collapse, reaching depths of 9m, measured 10m x 20m and extended into...

10th November 2016

Sinkhole at Towy View Park, Carmarthen, Wales

On 28th June 2016, a 10 metre by 10 metre sinkhole consumed gardens just metres behind homes on Towy View Park, Carmarthen, Wales. The sinkhole appeared early in the morning and almost...

29th June 2016

Sinkhole at New Build Development, Plumstead, London

On the 2nd May 2016 a sinkhole believed to be 60ft deep and 16ft wide opened up on the doorstep of one of Skillcrown Homes new developments within Brickfield Cottages, Plumstead. The result...

3rd May 2016

Sinkhole in Plantation Gardens, Norwich

On 9th April 2016, a 20-foot-deep sinkhole appeared at Norwich’s Plantation Garden, causing subsidence cracks to the neighbouring hotel on Earlham Road. This is a stone’s throw away from the...

26th April 2016

Sinkhole in Lawrence Square, Gravesend, Kent

In early 2015 at Lawrance Square, Northfleet, Gravesend, Kent – an extended period of subsidence culminating with the appearance of a sinkhole has forced several shops to close and evacuation...

6th January 2016

Sinkhole Makes Global News in St Albans, Hertfordshire

On 1st October 2015, a giant sinkhole opened up in Fontmell Close, St Albans forcing families to evacuate their homes and cutting off utilities to over 50 properties. A majority of Hertfordshire...

5th October 2015