Relics of mud volcanoes in the sedimentary cover of the South Caspian Basin

Forecast of Distribution and Thickness of Gas Hydrate Stability Zone at the Bottom of the Caspian Sea

“…The significant GH potential of the SC is additionally confirmed by numerous studies [30,31,33,37,[40][41][42], which show that the formation of GH is possible not only near mud volcanoes, but also in the sedimentary layers. However, despite a fairly large amount of actual materials, the upper part of the sedimentary cover of the Caspian Sea, especially in the MC region, is insufficiently studied.…”

“…Wide distribution of GH deposits in many deep areas of the World Ocean, including the continental slope of the Arctic Ocean, the Gulf of Mexico, the Norwegian, Black, Okhotsk, and Caspian seas, and the bottom of the Lake Baikal was also proven by direct exploration methods, as well as predicted based on indirect data [4,9,[20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36].…”

A New Mechanism for Earthquake‐Enhanced Permeability

“…Following the 2004 M9.2 Sumatra earthquake, for example, a well in southern China 3,200 km away from the epicenter blew out, and the groundwater fountain reached a height of 60 m above the ground surface (Che et al, 2009;Wang & Manga, 2021). Such large increase of pore pressure during earthquakes may disrupt the cohesion among sedimentary grains and deconsolidate layered sedimentary systems-a process documented by geophysical exploration at the base of thick (up to 15 km) sedimentary cover above the basement in South Sakhalin (Isaev et al, 2008) and invoked to explain the ascend of mud volcanoes from depths of ∼10 km (e.g., Guliyev & Huseynov, 2015). The relative rarity of such observations may be partly due to their large depths and partly due to that the process may require a combination of conditions in addition to the occurrence of a great earthquake (or the proximity to a major earthquake), such as nearby high-pressure sources.…”

“…We supported this hypothesis with geological records of injected sand dikes in impermeable cap rocks as evidence of pressurization and fluidization of deep aquifers, which have been documented by geological and geophysical investigations from different kinds of sedimentary basins worldwide (e.g., Huuse et al., 2010; Sherry et al., 2012). Liquefaction by seismic shaking has also been invoked to explain the ascend of mud eruptions (e.g., Guliyev & Huseynov, 2015; Huuse et al., 2010) that were imaged by seismic survey in deep (∼10 km) sedimentary basins (e.g., Guliyev & Huseynov, 2015). On the other hand, some questions remain difficult to answer.…”