Sand boil

Sand boils that erupted during the 2011 Canterbury earthquake.
Attempts to plug a sand boil with sandbags during the 2011 Missouri River floods. Many of the attempts were unsuccessful.
Sand boils and a silt-covered street after the 2011 Canterbury earthquake.

Sand boils, sand volcanoes, or sand blows occur when water under pressure wells up through a bed of sand.[1] The water looks like it is boiling up from the bed of sand, hence the name.

  1. ^ "Christchurch Earthquake – An Overview". Institution of Professional Engineers New Zealand. March 2011.