A Tectonic Pressure Cooker
The Andaman Sea Mud Volcano Field results from immense geological forces. Here, the Indian tectonic plate slides beneath the Burmese plate in a process called subduction. As the Indian plate descends, layers of sediment with organic material are scraped off and piled up, forming a massive wedge known as an accretionary prism. The Andaman Islands themselves are the surface expression of this prism.
Deep within this sediment pile, intense pressure and geothermal heat cook the trapped organic matter, generating vast quantities of methane gas. This gas mixes with pore water and fine-grained sediments to form a buoyant, pressurized slurry. This material forces its way to the seafloor through faults and fissures, erupting not as molten lava, but as a cold slurry of mud and gas. Seismic surveys reveal these structures as vertical, chaotic columns or "chimneys" piercing through sedimentary layers. The Indian National Gas Hydrate Program (NGHP) Expedition 01 confirmed the presence of one of the thickest and deepest gas hydrate stability zones in the world here, with hydrates stable at depths beyond 700 meters.
Life Without Sunlight
The constant seepage of methane and sulfides from the mud volcanoes supports dense biological communities that thrive in the complete absence of sunlight. Instead of photosynthesis, the food web is based on chemosynthesis. Specialized microbes including methanotrophic archaea and sulfide-oxidizing bacteria harness chemical energy from the seeping fluids. These microorganisms form the base of the food web, creating thick bacterial mats on the seafloor.
These microbial mats, in turn, provide food for a host of larger organisms. Entire ecosystems of tubeworms, clams, crabs, and shrimp flourish around the seeps. The biological activity is so intense that it alters the local geology. Over time, the metabolic byproducts of the microbes can lead to the formation of hard carbonate pavements on the otherwise soft, muddy seafloor. These hardgrounds are stable surfaces for other organisms like deep-sea corals and sponges to colonize, further increasing the area's biodiversity. The energy supplied by these chemical seeps accounts for an estimated 13 percent of the total energy entering the deep sea.