{"thcode":2,"term":{"code":1683,"name":"earth tides","parent":451,"scope":"Periodic changes in the earth surface topography caused by the gravitational attraction of the moon and sun, measured with tiltmeters.  Used in studies of volcanic activity."},"uf":[],"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":[],"rt":[]}