Azores tectonic or vulco-tectonic in nature, but in general low to medium intensities, occasionally punctuated by events of level 5 or greater on the Richter magnitude scale. The most severe earthquake was registered in 1757, near Calheta on the island of São Jorge, which exceeded 7 on the Richter magnitude scale. In comparison, the 1522 earthquake that was mentioned by historian Gaspar Frutuoso measured 6.8, but its effects were judged to be X ("Extreme") on the Mercalli intensity scale, and was responsible for the destruction of Vila Franca do Campo and landslides that may have killed more than 5,000 of the
Absolute magnitude using an absolute magnitude, one must specify the type of electromagnetic radiation being measured. When referring to total energy output, the proper term is bolometric magnitude. The bolometric magnitude usually is computed from the visual magnitude plus a bolometric correction, . This correction is needed because very hot stars radiate mostly ultraviolet radiation, whereas very cool stars radiate mostly infrared radiation (see Planck's law). Some stars visible to the naked eye have such a low absolute magnitude that they would appear bright enough to outshine the planets and cast shadows if they were at 10 parsecs from the Earth. Examples