Geohazards in the British Isles

Introduction

Geohazards are events caused by geological features and processes that present severe threats to humans, property, and the natural and built environment.
In the British Isles, geohazards primarily include earthquakes, landslides and flooding events, amongst others.

Earthquakes in the British Isles

Though not as common or as catastrophic as in other parts of the world, earthquakes do occur within the British Isles.
They are usually caused by tectonic stress associated with the collision of the Eurasian and African plates, compounded by isostatic rebound.
Out of these, the most significant known historical seismic event occurred in 1580, known as the Dover Straits Earthquake.
Modern instrumental records document a few hundred earthquakes each year, though many are too small to be felt by people.

Landslides in the British Isles

Landslides are a more common geohazard across the British Isles, often resulting from the saturation of permeable rock types situated above impermeable rock types.
Major factors influencing the occurrence of landslides include steep slope angles, weathering processes (such as freeze-thaw and dissolution), removing support at the bottom of slopes, loading the top of slides and earthquake shocks.
Notable examples of landslides in the British Isles include the Holbeck Hall landslide in 1993 in Scarborough, North Yorkshire.

Flooding in the British Isles

Flooding is perhaps the most prevalent geohazard in the British Isles, owing to the isles’ maritime climate.
Common causes of flooding include intense rainfall, rapid melting of snow, and failure of man-made structures like dams.
Two forms of flooding common in these regions are river (fluvial) flooding and coastal (marine) flooding.
Fluvial flooding is usually due to prolonged rainfall leading to increased run-off, or due to the melting of any snow.
Coastal flooding may occur as a result of sea level rise, severe storms, or tsunamis, though tsunamis are rarer.

Mitigation and Management of Geohazards in the British Isles

Mitigation measures for earthquakes may include the design and planning of buildings to withstand tremors, strict adherence to building regulations and codes, and public education about earthquake readiness.
Landslide mitigation approaches consist of correct land use planning, installation of drainage systems, slope stabilization and reinforcement.
Steps to mitigate flood hazards include construction of flood defences like embankments, river channelization, installation of flood gates, flood forecasting, and floodplain zoning.
An important aspect of geohazard management involves identifying areas of risk and developing geohazard risk maps.
Creating public awareness about geohazards, their causes, impacts, and potential mitigation strategies is crucial to reducing the impact of such events.

Understanding Geohazards: The Importance of Geology

Studying geohazards as part of geology offers important insights into the nature, causes and effects of such events, and potential strategies for hazard mitigation.
A clear understanding of geohazards is essential for effective land use planning and development, helping to shape public policy and informing risk management strategies.
It emphasizes the critical role geologists play in assessing geohazard risks and developing strategies to mitigate them.