the first embryonic surfaces started to appear in the waters of Santa Maria during the Miocene epoch (from circa 8 million years ago). The sequence of the island formation has been generally characterized as: Santa Maria (8.12 Ma), São Miguel (4.1 Ma), Terceira (3.52 Ma), Graciosa (2.5 Ma), Flores (2.16 Ma), Faial (0.7 Ma), São Jorge (0.55 Ma), Corvo (0.7 Ma) and the youngest, Pico (0.27 Ma). Although all islands have experienced volcanism during their geological history, within recorded "human settlement" history the islands of Santa Maria, Graciosa, Flores, and Corvo have not experienced any volcanic eruptions; in addition to active fumaroles and hot-springs, the remaining islands have had sporadic eruptions since the 14th century. Apart from the Capelinhos volcano in 1957–1958, the last recorded instance of "island formation" occurred off the coast of São Miguel, when the island of Sabrina was briefly formed. Earthquakes Owing to its geodynamic environment, the region has been a center of intense seismic activity, particularly along its tectonic boundaries on the Mid-Atlantic Ridge and Terceira Rift. Seismic events although frequent, are usually tectonic or vulco-tectonic in nature, but in general are of 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 inhabitants. Biome The archipelago lies in the Palearctic realm and has a unique biotic community that includes the Macaronesian subtropical laurissilva, with many endemic species of plants and animals. There are at least 6,112 terrestrial species, of which about 411 are endemic. The majority (75%) of these endemics are animals, mostly arthropods and mollusks. New species are found regularly in the Azores (e.g., 30 different new species of land snails were discovered circa 2013). Even though the Azores look very green and sometimes wild, the vegetation has been extremely altered. A great part of it has been wiped out in the past 600 years for its valuable wood (for tools, buildings, boats, fire wood, and so on) and to clear