Mud volcanoes are eruption of mud containing hydrocarbon fluids,
gases (methane, carbon dioxide, nitrogen) and acidic liquids with suspended
fine sediment.
These are more akin to mud diapirs formed by pressurised mud slarry. The muddy
material below ground are squeezed upward by compressive forces and expelled
at the surface along zones of weakness. Viscosity of the ejected mud ‘lava’ depends
on the content of the water, gas and/or oil content of the source rock/ clay.
Mud volcanoes are often associated with accretionary prism in subduction zones,
petroleum deposits and in orogenic belt. Internal forces below the earth's
surface causing mud volcanoes include tectonic disturbance, compression of
clays and differences in density and thickness of sediments. Hydrocarbon gases
are often associated. This gas is often the driving force, pushing mud from
deep within the earth upwards towards the surface.
The following movie [credit : Nitish Das, Geologist (Sr.),GSI] is taken on
17 December 2006 in the Baratang Island, Middle Andaman. Emanation of gas bubbles
and mud flows defined by dark hydrocarbon layering are well recorded.
If you have trouble viewing the movie then Click here
Andaman Islands a known locale for the occurrence of mud volcano, represent an accretionary prism in the fore arc of Sunda-Andaman Trench where downward plunging of the Indo- Australian plate is taking place beneath the Burmese plate in the Convergent Margin.
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last updated 17.1.2007