{"thcode":2,"term":{"code":1286,"name":"volcanic activity","parent":451,"scope":"Episodes during which gases, ash, and lava (molten rock) escape from vents in the earth's crust, accompanied by minor tremors."},"uf":[{"name":"eruption","usewith":false},{"name":"lava flows","usewith":false},{"name":"pyroclastic flows","usewith":false},{"name":"volcanic tremors","usewith":false},{"name":"volcanism","usewith":false},{"name":"volcano monitoring","usewith":{"code":375,"name":"field inventory and monitoring","parent":376,"scope":"Repeated observation or sampling at a site, on a scheduled or event basis, for study and analysis.  In general, this category excludes sampling programs in which materials are obtained in the field and brought back to a laboratory for study and analysis."}}],"bt":[{"code":451,"name":"geologic processes","parent":101,"scope":"All types of processes involving geological structures."},{"code":101,"name":"biological and physical processes","parent":1174,"scope":"All continuing activities, functions, and phenomena associated with organisms and non-living matter."},{"code":1174,"name":"topics","parent":1,"scope":"Themes, subjects, and concerns for which USGS information resources are relevant."},{"code":1,"name":"Categories","parent":null,"scope":"Thematic terms for categorizing information resources.  This thesaurus is intended to support finding and understanding scientific information."}],"nt":[{"code":1358,"name":"volcanic gas emission","parent":1286,"scope":"Emission of gases from fumaroles and volcanoes."}],"rt":[{"code":1694,"name":"aviation safety","parent":530,"scope":"Effects on air transportation of natural hazards such as volcanic activity (ash plumes and volcanic clouds)."},{"code":304,"name":"earthquakes","parent":451,"scope":"Ground shaking caused by the sudden release of accumulated strain by an abrupt shift of rock along a fracture in the earth or by volcanic or magmatic activity, or other sudden stress changes in the earth."},{"code":531,"name":"hazards","parent":1174,"scope":"Potential dangers from both natural processes (e.g., earthquakes, floods, and climate change) and human impacts on the environment."},{"code":1362,"name":"lahars","parent":639,"scope":"Downslope flow of ash and rock debris resulting from volcanic activity."},{"code":1145,"name":"tectonic processes","parent":451,"scope":"The structural forces affecting the deformation, uplift, and movement of the earth's crust."},{"code":1698,"name":"volcanic eruption prediction","parent":997,"scope":"Estimation of future volcanic activity using geological and geophysical observations."},{"code":1289,"name":"volcanology","parent":464,"scope":"The branch of geology that deals with volcanism and the processes involved in magma flow and eruption through a vent in the earth's surface."}]}