The USGS does not require a specific format when citing our websites. You should follow the citation guidelines provided by instructors or publication editors as appropriate.
Unless you're citing a specific USGS publication, the author of a USGS website is almost always "U.S. Geological Survey." Also acceptable: "United States Geological Survey" or "USGS."
Most USGS informational websites are updated/published daily, so you can generally use the current date as the publication date. For online datasets, you can also look in the metadata for a "last modified" date.
U.S. Geological Survey, 2020, Earthquake Lists, Maps, and Statistics, accessed March 18, 2020 at URL https://www.usgs.gov/natural-hazards/earthquake-hazards/lists-maps-and-statistics
U.S. Geological Survey, 2018, Water Science School: Acid Rain and Water at https://www.usgs.gov/special-topic/water-science-school/science/acid-rain-and-water. (Accessed May 14, 2018)
U.S. Geological Survey, 2020, National Water Information System data available on the World Wide Web (USGS Water Data for the Nation), accessed January 10, 2020, at URL https://waterdata.usgs.gov/nwis/
Learn more: USGS Data Citation