Segula Volcano
Encyclopedia
Segula Volcano lies 1228 miles (1,976 km) westward of Anchorage on the Segula Island
in the Aleutian Islands of Alaska. An inactive stratovolcano
, it has not produced any historical eruptions, while barely eroded deposits on the flanks suggest that activity took place at the volcano as late as a couple of hundred years ago.
Built on top of a shallow platform, the volcano grew steadily from eruptions, and is composed of strata
of flow deposits and pyroclastic material.
, Segula Volcano is located, along with the other Aleutians, in the Pacific Ocean. It is located in a row of islands which stretch from Kiska Island to as far east as the Andreanof Islands
.
Segula Island
and the volcano formed over an underwater land surface which hosts other Aleutian volcanoes such as Khvostof and Davidof
. Andesitic
lava and pyroclastic material was ejected from the underwater crater, building up over time to break the surface from nearly 350 feet (107 m) underwater.
Segula is made up of overlapping strata of lava flows and pyroclastic deposits, built up from the caldera. Largely built of eruptive material, the stratovolcano is conical and marked by a fissure. Since it is surrounded by lava flows on the north flank and a cinder cone
on the other, the mountain's caldera, or main crater, appears tiny and is therefore very difficult to make out from any photographs. The north side of the island is summarized by sharp cliffs and a shallow reef which together make accessibility from that side difficult. It has not had a recorded eruption, though numerous deposits of lava flows and other ejecta
on the southern and eastern flanks and a submarine deposit to the north of the summit which extends for 11 miles (18 km), make it possible that Segula has erupted in the last few hundred years.
Segula Island
Segula Island is an island in the Rat Islands archipelago of the western Aleutian Islands, Alaska. It consists of a Holocene stratovolcano, called Segula Volcano.Segula Island is three to four miles in diameter, and is located about east of Kiska Island...
in the Aleutian Islands of Alaska. An inactive stratovolcano
Stratovolcano
A stratovolcano, also known as a composite volcano, is a tall, conical volcano built up by many layers of hardened lava, tephra, pumice, and volcanic ash. Unlike shield volcanoes, stratovolcanoes are characterized by a steep profile and periodic, explosive eruptions...
, it has not produced any historical eruptions, while barely eroded deposits on the flanks suggest that activity took place at the volcano as late as a couple of hundred years ago.
Built on top of a shallow platform, the volcano grew steadily from eruptions, and is composed of strata
Stratum
In geology and related fields, a stratum is a layer of sedimentary rock or soil with internally consistent characteristics that distinguish it from other layers...
of flow deposits and pyroclastic material.
Geography and geology
Part of the Rat IslandsRat Islands
The Rat Islands are a volcanic group of islands in the Aleutian Islands in southwest Alaska, between Buldir Island and the Near Islands group to its west, and Amchitka Pass and the Andreanof Islands group to its east, at about ....
, Segula Volcano is located, along with the other Aleutians, in the Pacific Ocean. It is located in a row of islands which stretch from Kiska Island to as far east as the Andreanof Islands
Andreanof Islands
The Andreanof Islands are a group of islands in the Aleutian Islands in southwest Alaska. They are located between Amchitka Pass and the Rat Islands group to the west, and Amukta Pass and the Islands of Four Mountains group to the east, at about 52° North and 172°57' to 179°09' West. The islands...
.
Segula Island
Segula Island
Segula Island is an island in the Rat Islands archipelago of the western Aleutian Islands, Alaska. It consists of a Holocene stratovolcano, called Segula Volcano.Segula Island is three to four miles in diameter, and is located about east of Kiska Island...
and the volcano formed over an underwater land surface which hosts other Aleutian volcanoes such as Khvostof and Davidof
Davidof Volcano
Davidof Volcano is an inactive stratovolcano and caldera remnant in the Aleutian Islands of Alaska, USA, from Anchorage. Located on the eponymous island, Davidof is part of the Rat Islands sub-chain...
. Andesitic
Andesite
Andesite is an extrusive igneous, volcanic rock, of intermediate composition, with aphanitic to porphyritic texture. In a general sense, it is the intermediate type between basalt and dacite. The mineral assemblage is typically dominated by plagioclase plus pyroxene and/or hornblende. Magnetite,...
lava and pyroclastic material was ejected from the underwater crater, building up over time to break the surface from nearly 350 feet (107 m) underwater.
Segula is made up of overlapping strata of lava flows and pyroclastic deposits, built up from the caldera. Largely built of eruptive material, the stratovolcano is conical and marked by a fissure. Since it is surrounded by lava flows on the north flank and a cinder cone
Cinder cone
According to the , Cinder Cone is the proper name of 1 cinder cone in Canada and 7 cinder cones in the United States:In Canada: Cinder Cone In the United States:...
on the other, the mountain's caldera, or main crater, appears tiny and is therefore very difficult to make out from any photographs. The north side of the island is summarized by sharp cliffs and a shallow reef which together make accessibility from that side difficult. It has not had a recorded eruption, though numerous deposits of lava flows and other ejecta
Ejecta
Ejecta can mean:*In volcanology, particles that came out of a volcanic vent, traveled through the air or under water, and fell back on the ground surface or on the ocean floor...
on the southern and eastern flanks and a submarine deposit to the north of the summit which extends for 11 miles (18 km), make it possible that Segula has erupted in the last few hundred years.