Topics: Volcanology glossary | Earthquake glossary

Full glossary

Updated: May 1, 2025 21:34 GMT - refresh

Fajã de Cima volcan (Volcano): Nearly 200 scoria cones dot the "waist" of Sao Miguel Island between Sete Cidades and Agua de Pau volcanoes. Read all
Falso Azufre (Volcano): Falso Azufre volcano is a volcanic complex on the Chile/ Argentina border. The 15 km long complex contains overlapping craters and lava domes. The western part contains the highest peak, Cerro Falso Azufre.
Fantale (Volcano): Fantale (also spelled Fantalle, Fentale, or Fantala) is a large stratovolcano in the Ethiopian Rift Valley west of Lake Awash. It contains a large spectacular summit caldera.
Fantale's historic eruptions produced lava flows that descended to the east side into the valley and lake Awash. An eruption during the 13th century destroyed a town and church located south of the volcano. In 1820, a 4 km long fissure eruption occured on the east flank and sent basaltic lava flows both into the caldera and outside, reaching the bottom of the Rift valley. Read all
fault (Earthquakes): A fault is a fracture in the rigid crust of the earth, along which the two blocks on either side have moved relative to each other and often may do so again in the future. When blocks move along a fault, tectonic earthquakes are generated. Read all
Fayal (Volcano): The island of Fayal, also spelled Faial, is the nearest of the central Azorean islands to the Mid-Atlantic Ridge. Read all
feldspar (Minerals): Feldspars are a group of closely related rock-forming silicate minerals that are by far the most common in the earth's crust, making up about 41% of its weight.
Feldspar is the most common mineral formed during crystallization of magmas and almost always present in magmatic rocks.
Chemically, the feldspar minerals primarily bind varying proportions of the most common light elements potassium (K), sodium (Na), calcium (Ca), and aluminum (Al) ions, into a crystal lattice of silica (Si) ions. Read all
fissure vent (Volcanology): A fissure vent, also known as a volcanic fissure or simply fissure, is a linear volcanic vent through which lava erupts. Read all
Flores (Volcano): Flores Island and Corvo Island to its north are located far west of the rest of the Azores islands and are the only two Azorean volcanoes lying west of the Mid-Atlantic Ridge. Read all
focus Synonym of: hypocenter (Earthquakes)
foreshock (Earthquakes): Foreshocks are smaller earthquakes that precede the largest earthquake in a series, which is termed the mainshock. Not all earthquakes arre preceded by foreshocks. Read all
Fort Selkirk (Volcano): Fort Selkirk is a volcanic field near the junction of the Yukon and Pelly rivers in central Yukon. It is the northernmost young volcanic field in Canada.
The volcano consists of large valley-filling lava flows and 3 cinder cones.
The volcanic field developed at the intersection of two prominent fault lines, one running east-west, marked by the Pelly River and the lower Yukon River, and the other one NW-SE, defined by the upper Yukon River.
The first activity of the volcanic field were effusive, valley-filling eruptions of fluid basalt lava, followed by the construction of 3 cinder cones during strombolian-type eruptions and related emplacement of viscous aa lava flows. Read all
fossile (Geology): Fossils are the mineralized or otherwise preserved remains or traces (such as footprints) of animals, plants, and other organisms. Read all
Four Craters (Volcano): The Four Craters lava field, along with Devils Garden and Squaw Ridge, is the SE-most of a group of 3 basaltic lava fields SE of Newberry volcano in the High Lava Plains of central Oregon.
The Four Craters lava field contains 4 spatter cones along a 4-km-long NW-SE-trending line. The NW-most and highest cone has a well-preserved crater rim. The other 3 cones are breached to the west, SW, and south, respectively. The age of the Four Craters lava field is unknown, but probably similar to that of Squaw Ridge and Devils Garden, i.e. most likely about 10-20,000 years ago.
Fremrinamur (Volcano)
Fuego (Volcano): Fuego, one of Central America's most active volcanoes, is one of three large stratovolcanoes overlooking Guatemala's former capital, Antigua. It typically has strombolian activity and sometimes phases of intense lava fountaining, producing tall ash plumes and dangerous pyroclastic flows. Read all
Fueguino (Volcano): Fueguino (Volcán Cook) volcano is the southernmost active volcano of South America's Andes, located on Isla Cook. It is 400 km away from the nearest other active volcano, Monte Burney to the NW.
The volcano consists of lava domes and cinder cones. A strombolian eruption was observed in 1820. Read all
Fuerteventura (Volcano): Pleistocene and Holocene cinder cones and lava flows cover large portions of elongated Fuerteventura Island at the SE end of the Canary Islands. Read all
Fukue-jima (Volcano): Fukue (or Fukue-jima) volcano is a group of basaltic shield volcanoes and cinder cones on Fukue island off the western coast of Kyushu, Japan.
The volcanoes are 900,000 years old and last erupted about 2-3000 years ago. They are considered to be active.
The On-dake cinder cone forms the highest point of the volcanic field, which forms peninsulas at the eastern and SE tips of Fukue Island as well as several smaller islands SE of Fukue.
Fukujin (Volcano): Fukujin volcano is one of the largest seamounts of the Marianas arc in Japan's Volcano Island chain. It sometimes has risen to above surface during eruptions creating temporary new islands. Water discoloration and floating pumice above the submarine volcano have been observed frequently.
Fukutoku-Okanoba (Volcano): Fukutoku-Okanoba is a submarine volcano 5 km NE of the small pyramidal island Minami-iwo-jima in the Japanese Volcano Island chain. Eruptions and submarine hydrothermal activity often cause water discoloration in the area, and during eruptions, the volcano has built several temporary new islands. The first observation of a new island was in 1904-05 when it formed Shin-Iwo-jima ("New Sulfur Island"). Small new islands were also formed during the eruptions in 1914 and 1986. Read all
Furnas (Volcano): Furnas volcano lies at the eastern end of Sao Miguel Island, immediately west of the older Nordeste shield volcano and its Povoaçao caldera. Read all
Fuss Peak (Volcano): Fuss Peak is an isolated andesitic stratovolcano on southern Paramushir Island, Kuril Islands. The volcano rises almost 3000 m from the sea floor and forms a peninsula of Paramushir connected to it by a low isthmus.
The volcano contains a 700 m wide and 300 m deep crater, with a deep gully cutting its NW rim and forming a canyon down to the coast. Fresh-looking lava flows are on the E and SE flanks.
The last confirmed historic activity was in 1854.