Shallow geohazards

BGS Research

Geohazards, such as volcanoes, earthquakes and landslides, are the natural geological processes that present a direct risk to people or an indirect risk by impacting development. They can be subdivided between earth hazards , such as earthquakes, volcanoes and tsunamis, and shallow geohazards.

Shallow geohazards occur in the near-surface, typically including landslides, sinkholes and discontinuities that result from cambering or fault reactivation, as well as a range of hazards that occur as a consequence of karst and Quaternary processes. The term ‘shallow geohazard’ has also been extended by engineering geologists to embrace properties of geological materials that are a potential risk to infrastructure and include:

  • clay shrink-swell
  • collapsible soils
  • compressible soils
  • soluble rocks
  • ground gases
  • soil piping
  • soil geochemistry
  • running sand

The properties associated with each of these geohazards are sensitive to changes in moisture content and therefore to the consequences of climate change and  hydrohazards, including the various types of flooding: pluvial, fluvial and groundwater.

Collaborative shallow-geohazard research is important to society for planning and development and for infrastructure management.  In the international context, this research contributes to resilience through the United Nations’ Sustainable Development Goals.

The focus of BGS shallow geohazards research is on developing and communicating better understanding of distribution, characterisation, susceptibility and triggering and potential impacts of shallow geohazards.

The BGS is home to the National Landslide Database, the National Karst Database and a National Sinkhole Database. Data is collected using methods that range from Earth observation to literature searches, social media and crowd science. We draw from our researchers’ skills to respond to geohazard events, e.g. landslides induced by the Nepal earthquake of 2015 and sinkholes (e,g, Solotvyno, Ukraine), and we can assess data quality and representation in terms of size frequency distributions.

Conceptual classifications of shallow geohazards underpin geohazard communication, e.g. landslide, sinkhole and shrink–swell potential, which is based on the Atterberg limits of the soil and its position on the Casagrande plasticity chart.

Modelling commonly requires more specific, field-based information, e.g. dimensions, soil types and details of the triggering process. A number of techniques are used to collect this information, including Earth observation, ground based geomatics, geological and geomorphological mapping and  ground investigation techniques such as probing, drilling and shallow geophysics. Examples of this activity include responsive visit case studies and specific research projects, e.g. Aldbrough and Barton on Sea.

Algorithms, based on process understanding, are developed to identify areas where the ground conditions are more susceptible to geohazards, e.g.  BGS GeoSure  products. By adopting a domains approach, we are recognising that regions of common geology and geomorphology give rise to similar styles of geohazard. Perturbations (triggers) that initiate geohazards may be meteorological, tectonic (e.g. earthquakes) or anthropogenic.

Our shallow geohazard trigger threshold value research takes a number of approaches to identify hazard tipping points. Input data includes the monitoring data from geohazard observatories. By combining the concepts of susceptibility with MetOffice weather forecasting, we contribute to the Natural Hazards Partnership daily hazard assessment.  This is being advanced by domain-scale, real-time modelling.

By integrating susceptibility with hazard characterisation, we can better understand the potential impact of geohazards. Our research on this topic relies on both the development of impact libraries and modelling, which enable risk assessment and the provision of information for early warning systems to protect vulnerable communities and modelling for multihazard research.

Our shallow geohazards research

Limestone pavement, Cumbria

Sinkholes and karst research

Our research extends beyond the distribution and processes associated with sinkhole formation to the broader subject of karst.

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Downloading meteorological data

Hazard monitoring

Hazard monitoring provides valuable information for process understanding and for the science required for developing early warning systems to protect people and infrastructure.

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Thailand tsunami 2004

Tsunamis

Tsunamis are a truly, multihazard, global phenomena because the different mechanisms result in their wide geographic spread and impact.

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Soil piping

Soil piping

Soil piping is a naturally occurring hydraulic process that leads to the development of macropores (large air filled voids) in the sub-surface that are associated with landslides and collapse subsidence.

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Landslide_4_Feature

Hazard domains

The landslide domain map summarises the key characteristics of landslides in a series of hierarchical spatial units that represent areas of similar physiographic, meteorological, climatic and geological characteristics that shape the style of landsliding.

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Example of Valley bulging

Cambering, gulls and valley bulging

Cambering, gulls and valley bulging are responses to stress relief that results from rapid erosion of the landscape in conjunction with gravitational forces.

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Swelling and shrinking soils

Shrink–swell, or expansive, soils are one of the most costly and widespread geological hazards globally, with costs estimated to run into several billion pounds annually.

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Debris pathway downslope, partly netted. Debris on the railway line has been cleared and the line is in the process of being repaired.

Landslides

The BGS landslides team is involved in many aspects of landslide research, with the primary objective of building resilience both in the UK and internationally.

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Holbeck Hall Landslide

Natural Hazards Partnership

The NHP builds on the interdisciplinary expertise of its partners to deliver better coordinated natural hazards science, research and advice to Governments, Civil Contingency responders and other hazard resilience groups across the UK.

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