Base of hydrate stability zone for biogenic gas. Geographical site: world. Reference: Piñero, E., Marquardt, M., Hensen, C., Haeckel, M., & Wallmann, K. (2013). Estimation of the global inventory of methane hydrates in marine sediments using transfer functions. Biogeosciences (BG), 10(2), 959-975.

Density map of geothermal gradient developed with the “point density” algorithm of ArcGIS®. Pixel value, number of data per 100,000 km2. Parameters: population field, none; cell size, 5000; radius, 178,415 metres; areal units, square kilometres; method, geodesic. Knowledge gap, raster value < 1 Reference: https://doi.org/10.3390/app11062865

Seafloor features that are indicators for fluid flow. Represented as polygons

Geological/geochemical evidences and indicators for gas hydrate acquired from samples and cores. Data are represented as points.

Base of hydrate stability zone for biogenic gas. Geographical site: NW Europe. Reference: Váquez-Izquierdo, A., Gimenez-Moreno, C.-J., León, R., 2018. Knowledge gaps in gas-hydrate assessment: theoretical considerations and practical implications. Geophysical Research Vol. 20, EGU2018-12847, 2018EGU General Assembly 2018 (Vol. 20, EGU2018-12847, 2018EGU General Assembly 2018).

Geological/geochemical evidences of gas hydrate. Represented as polygons. Data from A.P. Karpinsky Russian Geological Research Institute

Geophysical indicators for gas hydrate. Data from Bundesanstalt für Geowissenschaften und Rohstoffe (BGR). Line data.

Density map of hydrate evidence (samples of hydrates in gravity cores or wells) and indicators (seismic anomalies or geochemical indicators). It has been developed with the “point density” algorithm of ArcGIS®. Pixel value, number of data per 100,000 km2. Parameters: population field, none; cell size, 5000; radius, 178,415 metres; areal units, square kilometres; method, geodesic. Knowledge gap, raster value < 1 Reference: https://doi.org/10.3390/app11062865

Density map of seafloor temperature developed with the “point density” algorithm of ArcGIS®. Pixel value, number of data per 100,000 km2. Parameters: population field, none; cell size, 5000; radius, 178,415 metres; areal units, square kilometres; method, geodesic. Knowledge gap, raster value < 1 Reference: https://doi.org/10.3390/app11062865

Geophysical indicators for gas hydrate. Polygons.