A sand geyser,sand fountain or sand blow is a
geologic phenomenon which occurs in association with
earthquakes and other
seismic events.[1] In the geologic record, these are seen as
clastic dikes.[2] It is described as "a geyser of sand and water that shoots from the ground during a major earthquake."[2][3] A quake can cause underlying sand to
liquefy while
pressure forces the eruption of the sand mixture to the surface.[4][5] The mixture of sand and water can also contain dissolved gases such as
methane and
carbon dioxide.[5]
Some investigators have located
soil formations that indicate the existence of past sand geysers in earthquake prone areas.[1]
NASA has proposed that the existence of sand geysers on the surface of
Mars explains some of the seasonal variations of light and dark areas. Plume-like markings that begin to appear during the martian spring may be caused by solid CO2 transforming explosively into its gaseous state causing an eruption of soil materials.[6]
A 2008 video recorded one eruption in
Saudi Arabia.[7] Another lay commentator attributed a similar event to differences in air temperature between underground pockets of air and the air above the ground.[8] The phenomenon was observed during an earthquake in
New Zealand in 1987.[9]