Sand boil: Difference between revisions

'''Sand boils''', '''sand volcanoes''', or '''sand volcanoesblows''' occur when water under pressure wells up through a bed of sand.<ref name=FACTSHEETIPENZ>{{cite news|title=Christchurch Earthquake -– An Overview|accessdate=6 March 2011|date=March 2011|agency=[[Institution of Professional Engineers New Zealand]]}}</ref> occur when water under pressure wells up through a bed of sand. The water looks like it is "boiling" up from the bed of sand, hence the name.

A '''sand volcano''' or '''sand blow''' is a cone of [[sand]] formed by the ejection of sand onto a surface from a central point. The sand builds up as a [[cone (geometry)|cone]] with slopes at the sand's [[angle of repose]]. A [[volcanic crater|crater]] is commonly seen at the [[summit (topography)|summit]]. The cone looks like a small [[volcanic cone]]<ref>[httphttps://www.flickr.com/search/?q=mollivan%20sand%20volcano&w=16921893%40N00] Images after [[2010 Canterbury earthquake]]</ref> and can range in size from millimetres to metres in diameter.

The process is often associated with [[earthquakesoil liquefaction]] and the ejection of fluidized sand that can occur in water-saturated sediments during an [[earthquake]]. The [[New Madrid Seismic Zone]] exhibited many such features during the [[18121811–12 New Madrid earthquake|1811-1812 series of earthquakes]].<ref name="usgs-nmsz-images">{{cite web |url=httphttps://earthquake.usgs.gov/earthquakes/states/events/1811-1812_pics.php |title=Historic Earthquakes: New Madrid Earthquakes 1811-18121811–1812 |work=[[United States Geological Survey]] |accessdate=March 7, 2010}}</ref> Adjacent sand blows aligned in a row along a linear fracture within fine-grained surface sediments are just as common, and can still be seen in the New Madrid area.

In the past few years, much effort has gone into the mapping of liquefaction features to study ancient earthquakes.<ref name="usgs00-0260">{{cite web |url=http://pubs.usgs.gov/of/2000/ofr-00-0260/ |title=Data for Quaternary Faults, Liquefaction Features, and Possible Tectonic Features in the Central and Eastern United States, East of the Rocky Mountain Front |work=United States Geological Survey |first1=Anthony J |last1=Crone |first2=Russell L |last2=Wheeler |year=2000 |id=Open-File Report 00-0260}}</ref> The basic idea is to map zones that are susceptible to the process and then go in for a closer look. The presence or absence of earthquake[[soil liquefaction]] features is strong evidence of past earthquake activity, or lack thereof.

A sand boil is difficult to stop. The most effective method is by creating a body of water above the boil to create enough pressure to slow the flow of water. A slower flow will not be able to move soil particles. The body of water is often created with [[sandbag]]s forming a ring around the boil.<ref>[http://cee.engr.ucdavis.edu/faculty/boulanger/geo_photo_album/Erosion%20and%20piping/Delta%20levee%20failure/Delta%20levee%20P1b.html UC Davis, Department of Civil & Environmental Engineering: Photograph of sandbag ring] {{waybackwebarchive |url=https://web.archive.org/web/20100611230547/http://cee.engr.ucdavis.edu/faculty/boulanger/geo_photo_album/Erosion%20and%20piping/Delta%20levee%20failure/Delta%20levee%20P1b.html |date=20100611230547June 11, 2010 }}</ref>

During the flood of spring 2011, the [[United States Army Corps of Engineers]] had to work to contain the largest sand boil ever discovered. The sand boil measured 309 feetby 12 meters (30 by 40 feet) and was located in the city of [[Cairo, Illinois]], at the confluence of the [[Mississippi River]] and the [[Ohio River]].<ref>[http://www.wpsdlocal6.com/news/local/Sand-boils-may-cause-levee-breach-121028764.html wpsdlocal6.com] {{waybackwebarchive |url=https://web.archive.org/web/20110504013219/http://www.wpsdlocal6.com/news/local/Sand-boils-may-cause-levee-breach-121028764.html |date=20110504013219May 4, 2011 }}</ref>

An example of this is during the 1989 earthquake in [[San Francisco]], when sand boils brought up debris from the [[1906 San Francisco earthquake|1906 earthquake]]. This process is a result of [[liquefaction]]. By mapping the location of sand boils that erupted in the Marina District during the 1989 Loma Prieta earthquake, scientists discovered the site of a lagoon that existed in 1906. The lagoon developed after the Fair's Seawall was constructed, and was later filled in<!--not a mistake--> in 1915 in preparation for the Panama-Pacific[[Panama–Pacific International Exposition]].<ref>{{cite journal|last1=Bardet|first1=J.P.|last2=Kapuskar|first2=M.|title=The Liquefaction Sand Boils in the San Francisco Marina District During the 1989 Loma Prieta Earthquake|journal=Conference Proceedings, Second International Conference on Recent Advances in Geotechnical Earthquake Engineering & Soil Dynamics|date=March, 1991|issue=Paper 19|url=http://scholarsmine.mst.edu/cgi/viewcontent.cgi?article=3629&context=icrageesd}}</ref>