Gas hydrate is a solid crystalline material composed of water and natural gas that forms at low temperature and high pressure. Gas hydrates represent an important reservoir of natural gas, even if the actual global estimate is very rough. The increasing attention about gas hydrates is rising from (1) the assessment of methane hydrates as a new ‘clean’ energy source, (2) the relationship between gas hydrate and global climate, and (3) the geological hazard related to the gas hydrate.

Generally, gas hydrate deposits are investigated by using several geophysical methods. The seismic technique, which is the most used, allows detecting a clear indicator of the hydrate and free gas accumulations, known as bottom simulating reflector. Moreover, the seismic data provides information about the geometry of the main geological structures, allowing possible explanations of the presence/absence of gas hydrate on continental margins. In the last years, the scientific community starts to integrate geophysical (mainly seismic and electromagnetic data), geochemical, and heat-flow data in order to detect and characterize gas hydrate and free gas volumes and distribution in the marine sediments. Thus, reviews of extensive geophysical surveys and direct measurements combined with geological interpretation and theoretical modeling will increase understanding on the occurrence, distribution, and concentration of gas hydrate and the underlying free gas beneath the ocean bottom.

We invite authors to submit original research and review articles on the subject. Potential topics include, but are not limited to:

• Information on hydrate and/or free gas concentration and distribution obtained by direct and indirect measurements
• New information on the relationships between geophysical response and hydrate occurrence
• Geological aspect related to the gas hydrate presence/absence

Before submission authors should carefully read over the journal's Author Guidelines, which are located at http://www.hindawi.com/journals/jgr/guidelines/. Prospective authors should submit an electronic copy of their complete manuscript through the journal Manuscript Tracking System at http://mts.hindawi.com/ according to the following timetable: