Holbeck Hall - Consequences Of Coastal Erosion (Landslide)

Question 1

What causes a Landslide?

Answer 1

Landslides occur when the water (from rainfall) is absorbed from permeable, soft rock which causes the rock to become heavier, less structured (weaker) and lubricated which causes the land to slide (landslide)

Question 2

Background of Holbeck Hall Cliff

Answer 2

• In 1993, Holbeck cliff had a landslide (mudflow) that led to the loss of Holbeck Hall Hotel
• The cliffs are around 65-70m high and developed in a sequence of glacial tills (boulder clay) overlying mudstones and siltstones
• Prior to landslide, cliff had sloped 35 degrees becoming steeper at the base where there was a sea wall and promenade which provided protection from wave attack

Question 3

Management Strategies at Holbeck Hall

Answer 3

• After landslide, emergency coast protection and cliff stabilization works were undertaken to prevent rapid landward spread of the landslide, at a cost of £2 million.
  Purpose: prevent toe erosion (would activate landslide) & the landward expansion of the landslide and further loss of property

Strategies:
Rock armour revetment
Placed at toe of the eroding front of the landslide debris lobe on shore platform. Design included 30,000 tonnes of rock placed against heavy duty geo-textile bags filled with slip material

Failed slope was re-profiled
Sloped to an angle of 24 degrees. Slope was compacted and sealed to reduce infiltration and minimise surface erosion

Slope drainage
Including interceptor drain at cliff top, a perimeter drain and localised pipe drains

Question 4

Social-economic Consequences of Erosion at Holbeck Hall

Answer 4

+ No lives lost or anyone injured

• The loss of Holbeck Hall Hotel could have caused people to lose their jobs, which may have left them economically unstable
• A fall of tourism may have occurred due to the beach becoming unattractive, less accommodation or threat of safety. This decreases economy in Scarborough
• Very expensive coastal management put in place

Question 5

Physical Consequences of Erosion at Holbeck Hall

Answer 5

• 55m of the 70m garden at Holbeck Hall Hotel had eroded by 6am on the 4th June 1993
• The east wing of the Holbeck Hall Hotel collapsed by the evening of 5th June 1993
  1 million tonnes of glacial till cut back the 60m high cliff by 70m
• A semi-circular promontory was formed which was 200m wide projecting 135m outward from the foot of the cliff