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    "en": "Liquefaction (Groundwater Trigger)"
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    "en": [
      "Boiling sand",
      "Quick sand,",
      "Running sand,"
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    "en": "Liquefaction is the term applied to the loss of strength experienced in loosely packed, saturated or close to saturated sediments at or near the ground surface in response to strong ground shaking, such as earthquakes, cyclic loading, and vibration from machinery, or due to the development of excess pore pressure resulting from a change in head or confining pressures. The loss of strength causes the soil to behave like a viscous fluid, sometimes referred to as ‘running sand’, until the excess pore pressure returns to hydrostatic (USGS, no date). <br /> <p>USGS, no date. <a href=\"https://www.usgs.gov/news/science-snippet/earthword-liquefaction\">Science Explorer: Liquefaction. United States Geological Survey (USGS)</a>. Accessed 12 October 2020.</p>"
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    "en": [
      "Soil propensity to liquefaction has been related to grading, uniformity of grain size and relative density or voids ratio. A uniformly graded soil is more susceptible to soil liquefaction than a well-graded soil because the resistance to volumetric strain of a well-graded soil decreases the amount of excess pore pressure that can develop under undrained conditions. Historically, sands were considered to be the only type of soil susceptible to liquefaction. Yet, liquefaction also occurs in gravel and silt (Seed et al., 2003). ‘Running sand’ or ‘boiling sand’ is a product of the liquefaction process that can also occur in peat. Liquefaction susceptibility is also influenced by particle shape; soil deposits with rounded particles being more susceptible to liquefaction than soils with angular particles. Structureless anthropogenic soils, such as those placed during land reclamation are susceptible to liquefaction. During construction, liquefaction occurs when the groundwater conditions reduce the effective stress of the soil to zero. At this point, the seepage pressure can disturb the soil structure and mobilise the sediment as quick, running or boiling sand (BRANZ Seismic Resilience, no date). Liquefaction, as a secondary hazard associated with earthquakes, can also manifest via surface ruptures and fissures, as seen in Christchurch, New Zealand in 2011 (Cubrinovski, 2013). The liquefaction associated with the Christchurch earthquakes caused significant disruption to transport infrastructure, and to storm- and wastewater networks, and posed physical and mental health hazards for the exposed community and clean-up (Villemure et al., 2012). From a human health perspective, the liquefaction material posed several hazards. Due to the extensive damage to the sewage disposal networks from lateral spreading and differential settlement, there was a risk that much of the liquefaction ejecta had been contaminated with raw sewage creating a long-term health risk to the population. During hot and windy conditions, the dry finer portions of silt were mobilised by the wind creating a possible respiratory health hazard. Many volunteers were involved in the clean-up operations. Indeed, the much-celebrated Student-Army was successfully used to coordinate the work around the city (Villemure et al., 2012)."
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