Tucked in a grove of thorny mesquite trees, on an ancient coral reef on the south side of the Hawaiian island of Oahu, west of Pearl Harbor, a small unmanned observatory quietly records the Earth’s time-varying magnetic field. The Honolulu Magnetic Observatory is 1 of 14 that the U.S. Geological Survey Geomagnetism Program operates at various locations across the United States and its territories.
Data from these observatories, Honolulu, and those operated by institutions in foreign countries, record a variety of magnetic signals related to a wide diversity of physical phenomena in the Earth’s interior and its surrounding outer-space environment. USGS magnetic observatory operations are an integral part of a U.S. National Space Weather Strategy for monitoring and assessing natural hazards that potentially threaten important technological systems.