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 with slopes at the sand's angle of repose. A crater is commonly seen at the summit. The cone looks like a small volcanic cone and can range in size from millimetres to metres in diameter. For other uses, see Sand (disambiguation). ... In common usage and elementary geometry, a cone (Greek: κώνος) is a solid object obtained by rotating a right triangle around one of its two short sides, the cones axis. ... For the engineering term, see Angle of repose. ... Perhaps the most conspicuous part of a volcano is the crater, a basin of a roughly circular form within which occurs a vent (or vents) from which magma erupts as gases, lava, and ejecta. ... A topographical summit is a point on a surface which is higher in elevation than all points immediately adjacent to it. ... Pu‘u ‘Ō‘ō, a cinder-and-spatter cone on Kilauea, Hawaii Volcanic cones are among the simplest volcano formations. ...

The process is often associated with earthquake 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 1811-1812 series of earthquakes. [1] Linear sand blows are just as common, and can still be seen in the New Madrid area. I LIKE MARSHMELLOWS float in a liquid slurry. ... Global earthquake epicenters, 1963–1998 An earthquake is a sudden and sometimes catastrophic movement of a part of the Earths surface. ... Seismic map New Madrid Seismic Zone. ... The New Madrid Earthquake, the largest earthquake ever recorded in the continental United States, occurred on February 7, 1812. ...

In the past few years, much effort has gone into the mapping of liquefaction features to study ancient earthquakes [2]. 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 liquefaction features is strong evidence of past earthquake activity, or lack thereof.

These are to be contrasted with mud volcanoes which occur in areas of geyser or subsurface gas venting. The term mud volcano or mud dome is used to refer to formations created by geologically excreted liquids and gases, although there are several different processes which may cause such activity. ... Clepsydra Geyser in Yellowstone A geyser is a type of hot spring that erupts periodically, ejecting a column of hot water and steam into the air. ...

External links

• USGS photo
• Site on newly emerged mud volcanoes