Geohazard
Encyclopedia
A geohazard can be defined as a geological state that represents or has the potential to develop further into a situation leading to damage or uncontrolled risk. This definition implies that geohazards are widespread phenomena that are related to geological and environmental conditions and involve long-term and/or short-term geological processes. Geohazards can thus be relatively small features, but they can also attain huge dimensions (e.g. submarine or surface landslide
) and affect local and regional socio-economy (e.g. tsunami
s) to a large extent. In addition, human activities - for example drilling through geohazards like overpressured zones - could result in significant risk, and as such mitigation and prevention are paramount, through improved understanding of geohazards, their preconditions, causes and implications. In other cases, particularly in montane regions, natural processes can cause catalytic events of a complex nature, such as an avalanche
hitting a lake causes a debris flow, with consequences potentially hundreds of miles away, or a lahar released by volcanism.
The continued and multi-disciplinary investigation into the occurrence and implications of geohazards, in particular offshore geohazards in relation with the oil and gas exploration, lead to specific mitigation studies and establishing relevant prevention mechanisms.
Landslide
A landslide or landslip is a geological phenomenon which includes a wide range of ground movement, such as rockfalls, deep failure of slopes and shallow debris flows, which can occur in offshore, coastal and onshore environments...
) and affect local and regional socio-economy (e.g. tsunami
Tsunami
A tsunami is a series of water waves caused by the displacement of a large volume of a body of water, typically an ocean or a large lake...
s) to a large extent. In addition, human activities - for example drilling through geohazards like overpressured zones - could result in significant risk, and as such mitigation and prevention are paramount, through improved understanding of geohazards, their preconditions, causes and implications. In other cases, particularly in montane regions, natural processes can cause catalytic events of a complex nature, such as an avalanche
Avalanche
An avalanche is a sudden rapid flow of snow down a slope, occurring when either natural triggers or human activity causes a critical escalating transition from the slow equilibrium evolution of the snow pack. Typically occurring in mountainous terrain, an avalanche can mix air and water with the...
hitting a lake causes a debris flow, with consequences potentially hundreds of miles away, or a lahar released by volcanism.
The continued and multi-disciplinary investigation into the occurrence and implications of geohazards, in particular offshore geohazards in relation with the oil and gas exploration, lead to specific mitigation studies and establishing relevant prevention mechanisms.
Examples of geohazards
- (Submarine) LandslideLandslideA landslide or landslip is a geological phenomenon which includes a wide range of ground movement, such as rockfalls, deep failure of slopes and shallow debris flows, which can occur in offshore, coastal and onshore environments...
s - Debris flowDebris flowA debris flow is a fast moving, liquefied landslide of unconsolidated, saturated debris that looks like flowing concrete. It is differentiated from a mudflow in terms of the viscosity and textural properties of the flow. Flows can carry material ranging in size from clay to boulders, and may...
s - Shallow gasGasGas is one of the three classical states of matter . Near absolute zero, a substance exists as a solid. As heat is added to this substance it melts into a liquid at its melting point , boils into a gas at its boiling point, and if heated high enough would enter a plasma state in which the electrons...
accumulation - Overpressured zones (including gas and shallow water flows)
- Naturally occurring gas hydratesClathrate hydrateClathrate hydrates are crystalline water-based solids physically resembling ice, in which small non-polar molecules or polar molecules with large hydrophobic moieties are trapped inside "cages" of hydrogen bonded water molecules...
and their climate-controlled meta-stability - Mud flows, diapirism and mud volcanism/mud volcanoMud volcanoThe term mud volcano or mud dome are used to refer to formations created by geo-excreted liquids and gases, although there are several different processes which may cause such activity. Hot water mixes with mud and surface deposits. Mud volcanoes are associated with subduction zones and about 700...
es - EarthquakeEarthquakeAn earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time...
s and seismicitySeismologySeismology is the scientific study of earthquakes and the propagation of elastic waves through the Earth or through other planet-like bodies. The field also includes studies of earthquake effects, such as tsunamis as well as diverse seismic sources such as volcanic, tectonic, oceanic,... - TsunamiTsunamiA tsunami is a series of water waves caused by the displacement of a large volume of a body of water, typically an ocean or a large lake...
s from tectonicsTectonicsTectonics is a field of study within geology concerned generally with the structures within the lithosphere of the Earth and particularly with the forces and movements that have operated in a region to create these structures.Tectonics is concerned with the orogenies and tectonic development of...
and landslideLandslideA landslide or landslip is a geological phenomenon which includes a wide range of ground movement, such as rockfalls, deep failure of slopes and shallow debris flows, which can occur in offshore, coastal and onshore environments...
s - Rock fallsRockfallRockfall or rock-fall refers to quantities of rock falling freely from a cliff face. A rockfall is a fragment of rock detached by sliding, toppling, or falling, that falls along a vertical or sub-vertical cliff, proceeds down slope by bouncing and flying along ballistic trajectories or by rolling...
and landslideLandslideA landslide or landslip is a geological phenomenon which includes a wide range of ground movement, such as rockfalls, deep failure of slopes and shallow debris flows, which can occur in offshore, coastal and onshore environments...
s