USGS Home
Contact USGS
Search USGS

Title Page - What - Where - Why - How - Who - Resources - Bermuda Triangle - Web Sites

Gas Hydrate: Where is it found?

Since the 1970's, naturally occurring gas hydrate, mainly methane hydrate, has been recognized worldwide, where pressure and temperature conditions stabilize the hydrate structure. It is present in oceanic sediments along continental margins and in polar continental settings. It has been identified from borehole samples and by its characteristic responses in seismic-reflection profiles and oil-well electric logs. Beneath the ocean, gas hydrate exists where water depths exceed 300 to 500 meters (depending on temperature), and it can occur within a layer of sediment as much as ~1000 meters thick directly beneath the sea floor; the base of the layer is limited by increasing temperature. At high latitudes, it exists in association with permafrost.

Four regions of gas hydrate concentration have been mapped on the continental rise in the offshore region between New Jersey and Georgia. Three are correlated with sediment depocenters and one occurs along a concentration of salt diapirs and their associated faults.

Off the southeastern United States, a small area (only 3000 km²) beneath a ridge formed by rapidly-deposited sediments appears to contain a volume of methane in hydrate that is equivalent to ~30 times the U.S. annual consumption of gas. This area is known as the Blake Ridge. Significant quantities of naturally occurring gas hydrate also have been detected in many regions of the Arctic, including Siberia, the Mackenzie River delta, and the north slope of Alaska.

Title Page - What - Where - Why - How - Who - Resources - Bermuda Triangle - Web Sites