Near sea-floor methane hydrate is being continuously broken down, releasing methane dissolved in pore water. As methane moves through sediment into the water column and atmosphere, it is consumed in a variety of chemically and microbially controlled reactions. Figure is not drawn to scale. For hydrates in the marine environment, the water depth (Zone 3) would generally be 300-500 metres or more, Zone 2 would be on the order of 1 centimetre thick, and Zone 1 would be on the order of 10 metres thick.
From collection: Frozen Heat - A Global Outlook on Methane Gas Hydrates