March 27 · This Day in America
It is Good Friday, early evening, and southern Alaska is settling in for the holiday when the earth begins to roll. The Great Alaska Earthquake registers magnitude 9.2, the most powerful ever recorded in North America and the second largest anywhere. For roughly four and a half minutes the ground heaves like water. Streets in Anchorage split open and drop away. Whole neighborhoods slide toward the sea. Tsunamis race across the Pacific, killing people as far as California. About one hundred thirty people die. Out of the wreckage came something unexpected: a young USGS geologist named George Plafker reads the risen and sunken coastline and recognizes the signature of a subduction zone, hard evidence for the then-new theory of plate tectonics. The disaster helped us finally understand how the planet itself is built.
Source: earthquake.usgs.gov
Also on this day · 1513
On Easter season, the lookouts on Juan Ponce de León's small fleet spot a long green shore rising out of the sea. He names it La Florida, for the Spanish feast of flowers and for the land itself. He would not step ashore for days, and others may have glimpsed it before him, but this is the first recorded European sighting of what is now the continental United States. The map of the world quietly grew a new edge.
Source: www.britannica.com