Atlantis Online
April 19, 2018, 05:55:43 pm
Welcome, Guest. Please login or register.

Login with username, password and session length
News: Ancient Crash, Epic Wave
http://www.iht.com/articles/2006/11/14/healthscience/web.1114meteor.php?page=1

 
  Home Help Arcade Gallery Links Staff List Calendar Login Register  

ATLANTIS & the Atlantic Ocean

Pages: 1 ... 18 19 20 21 22 23 [24] 25   Go Down
  Print  
Author Topic: ATLANTIS & the Atlantic Ocean  (Read 17173 times)
dhill757
Administrator
Superhero Member
*****
Posts: 3853



« Reply #345 on: March 30, 2009, 12:01:53 am »



 Corvo


A 2-km-wide caldera containing several small cinder cones and two shallow lakes is the most prominent feature in this NASA Space Shuttle image with north to the left. Two pyroclastic cones erupted along a N-S-trending fissure outside the caldera fed lava flows that formed a platform that underlies the peninsula at the southern end of the island. The 3.5 x 6 km island of Corvo and its neighbor to the south, Flores (far right), are the only two Azorean volcanoes located west of the Mid-Atlantic Ridge.

NASA Space Shuttle image ISS007-E-11252, 2003 (http://eol.jsc.nasa.gov/).
 Corvo

 Country: Portugal
Subregion Name: Azores and Madeira
Volcano Number: 1802-002
Volcano Type: Stratovolcano
Volcano Status: Holocene
Last Known Eruption: Unknown
Summit Elevation: 718 m 2,356 feet
Latitude: 39.699°N  39°41'56"N
Longitude: 31.111°W 31°6'39"W
The small 3.5 x 6 km island of Corvo is located at the NW end of the Azores archipelago. Corvo and its neighbor to the south, Flores, are the only two Azorean volcanoes located west of the Mid-Atlantic Ridge. A 2-km-wide caldera centered on the north side of the island is the most prominent feature of Corvo. The caldera floor contains several small cinder cones and two shallow lakes. Two southward-breached pyroclastic cones erupted along a N-S-trending fissure and fed lava flows that formed a platform that underlies the village of Corvo at the southern end of the island. The youngest eruption on Corvo produced a fissure-fed lava flow that reached the sea near Punta Negra. 
Report Spam   Logged
dhill757
Administrator
Superhero Member
*****
Posts: 3853



« Reply #346 on: March 30, 2009, 12:02:31 am »



   
 Fayal

 Country: Portugal
Subregion Name: Azores and Madeira
Volcano Number: 1802-01=
Volcano Type: Stratovolcano
Volcano Status: Historical
Last Known Eruption: 1958   
Summit Elevation: 1043 m 3,422 feet
Latitude: 38.60°N  38°36'0"N
Longitude: 28.73°W 28°44'0"W
The island of Fayal, also spelled Faial, is the nearest of the central Azorean islands to the Mid-Atlantic Ridge. The island is composed of a complex large andesitic-to-trachytic stratovolcano that contains a 2-km-wide summit caldera. Thick deposits of trachytic airfall pumice, pyroclastic flows, and lahars related to formation of the caldera blanket the island. Formation of the steep-walled 500-m-deep caldera was followed by construction of fissure-fed basaltic lava fields and small volcanoes that form a peninsula extending to the west. This area is covered by the youngest volcanic products on the island and has been the source of all historical eruptions. A dramatic submarine eruption at Capelinhos during 1957-58, the best-studied of historical eruptions in the Azores, created a new island that soon merged with the western peninsula. 


Fayal volcano is capped by a 2-km-wide, 500-m-deep summit caldera, seen from its southern rim. A small pyroclastic cone was constructed on the floor of the caldera. Thick airfall-pumice and pyroclastic-flow deposits related to formation of the caldera blanket the island. This event was followed by construction of fissure-fed lava fields and small volcanoes that formed a peninsula extending to the west. A dramatic submarine eruption at Capelinhos during 1957-58 created a new island that soon merged with the western peninsula.

Photo by Rick Wunderman, 1997 (Smithsonian Institution).

Report Spam   Logged
dhill757
Administrator
Superhero Member
*****
Posts: 3853



« Reply #347 on: March 30, 2009, 12:03:04 am »



   
Pico stratovolcano occupying the eastern end of Pico Island rises across a strait SE of neighboring Fayal Island (foreground). Pico is superimposed on an older linear volcano with numerous flank cones that forms most of the eastern side of the 48-km-long island. The conical Pico volcano is capped by a 500-m-wide summit crater that is overtopped by a small steep-sided cone visible at the left side of the summit. Historical eruptions have been restricted to the flanks of Pico volcano itself and to the SE-trending rift zone.

Photo by Rick Wunderman, 1997 (Smithsonian Institution).



 Country: Portugal
Subregion Name: Azores and Madeira
Volcano Number: 1802-02=
Volcano Type: Stratovolcano
Volcano Status: Historical
Last Known Eruption: 1720   
Summit Elevation: 2351 m 7,713 feet
Latitude: 38.47°N  38°28'0"N
Longitude: 28.40°W 28°24'0"W
A prominent 2351-m-high stratovolcano occupying the eastern end of Pico Island is the highest volcano in the Azores. Pico is superimposed on an older linear volcano with numerous flank cones that forms most of the 48-km-long island. The conical, dominantly basaltic Pico volcano is capped by a 500-m-wide summit crater that is overtopped by a small steep-sided cone. Historical eruptions have been restricted to the flanks of Pico volcano and to the SE-trending rift zone, which is dotted by pyroclastic cones. An eruption during 1562-64 from the SE rift zone produced lava flows that reached the northern coast. An eruption from a nearby vent issued lava flows that traveled into the sea on the southern side of the island. A flank eruption from Pico in 1718 fed lava flows that reached both coasts.



http://www.volcano.si.edu/world/region.cfm?rnum=1802
Report Spam   Logged
dhill757
Administrator
Superhero Member
*****
Posts: 3853



« Reply #348 on: March 30, 2009, 12:03:32 am »



San Jorge

A Space Shuttle image with north to the upper left shows the remarkably linear island of San Jorge (Sao Jorge), which is 54 km long and only 5 km wide. The NW-SE-trending island was formed by fissure-fed eruptions. Historical eruptions in 1580 AD originated from three locations above and to the east of the coastal town of Velas, the small light-colored area along the SW coast (bottom left side), producing lava flows that reached the sea. Submarine eruptions were reported on several occasions from vents off the southern and SW coasts.

NASA Space Shuttle image ISS004-E-10891, 2002 (http://eol.jsc.nasa.gov/).


 Country: Portugal
Subregion Name: Azores and Madeira
Volcano Number: 1802-03=
Volcano Type: Fissure vent
Volcano Status: Historical
Last Known Eruption: 1907   
Summit Elevation: 1053 m 3,455 feet
Latitude: 38.65°N  38°39'0"N
Longitude: 28.08°W 28°5'0"W
The remarkably linear island of San Jorge (Sao Jorge) is 54 km long and only 5 km wide. It was formed by fissure-fed eruptions beginning in the eastern part of the island. The western two-thirds of dominantly basaltic San Jorge contains youthful, fissure-fed lava flows resembling those on neighboring Pico Island. Subaerial lava flows issued from three locations above the south-central coast during 1580, producing lava flows that reached the sea. In 1808 a series of explosions took place from vents along the south-central crest of the island; one of these fed a lava flow that also reached the southern coast. Submarine eruptions were reported on several occasions from vents off the southern and SW coasts. 
Report Spam   Logged
dhill757
Administrator
Superhero Member
*****
Posts: 3853



« Reply #349 on: March 30, 2009, 12:03:54 am »



   Graciosa 

The small 4 x 8 km island of Graciosa is seen in this NASA Space Shuttle image with north to the upper left. Cloud banks partially obscure the SE end of the island, which contains a small 0.9 x 1.6 km caldera with active fumaroles. Scoria cones are found over much of the island, and several widely spaced NE-SW-trending fissures fed a youthful lava field that forms the NW end of the island.

NASA Space Shuttle image ISS004-E-10893, 2002 (http://eol.jsc.nasa.gov/).


 Country: Portugal
Subregion Name: Azores and Madeira
Volcano Number: 1802-04=
Volcano Type: Stratovolcano
Volcano Status: Holocene
Last Known Eruption: Unknown
Summit Elevation: 402 m 1,319 feet
Latitude: 39.02°N  39°1'0"N
Longitude: 27.97°W 27°58'0"W
The SE end of Graciosa, the northernmost of the central Azorean islands, contains a small 0.9 x 1.6 km caldera with active fumaroles. The 402-m-high SE caldera rim is the high point of the small 4 x 8 km island. The caldera has been the source of eruptions producing significant tephra falls, pyroclastic flows, lahars, and lava flows. An important fumarole field is located in a volcanic cave inside the caldera, and a submarine fumarole occurs off the NW coast of Graciosa. Scoria cones erupted along several widely spaced NE-SW-trending fissures fed a youthful lava field that forms the NW end of the island. The most recent eruption from Pico Tomao, NW of the caldera, produced a lava flow that reached the eastern coast NW of the village of Praia. 
Report Spam   Logged
dhill757
Administrator
Superhero Member
*****
Posts: 3853



« Reply #350 on: March 30, 2009, 12:04:19 am »



   Terceira 



Terceira Island, seen here from the Space Shuttle, contains four stratovolcanoes constructed along a prominent ESE-WNW-trending fissure zone cutting across the island. The summit caldera of Santa Barbara, the westernmost volcano (and the only one active during historical time) is the dark-colored area at the left. Cinco Picos caldera can be faintly seen at the center, with the broad Guilherme Moniz caldera at the right. Historical eruptions have taken place from the rift zone and offshore vents.

NASA Space Shuttle image ISS004-E-10890, 2002 (http://eol.jsc.nasa.gov/).



 Country: Portugal
Subregion Name: Azores and Madeira
Volcano Number: 1802-05=
Volcano Type: Stratovolcanoes
Volcano Status: Historical
Last Known Eruption: 2000   
Summit Elevation: 1023 m 3,356 feet
Latitude: 38.73°N  38°44'0"N
Longitude: 27.32°W 27°19'0"W
Terceira Island contains four stratovolcanoes constructed along a prominent ESE-WNW-trending fissure zone that cuts across the island. Historically active Santa Barbara volcano at the western end of the island is truncated by two calderas. The youngest of these formed about 15,000 years ago. Comenditic lava domes fill and surround the caldera. Pico Alto lies north of the fissure zone in the north-central part of the island and contains a Pleistocene caldera largely filled by lava domes and lava flows. Guilherme Moniz caldera lies along the fissure zone immediately to the south, and 7-km-wide Cinquio Picos caldera at the SE end of the island is the largest in the Azores. Historical eruptions have occurred from Pico Alto, the fissure zone between Pico Alto and Santa Barbara, and from submarine vents west of Santa Barbara. Most Holocene eruptions have produced basaltic-to-rhyolitic lava flows from the fissure zone transecting the island.
Report Spam   Logged
dhill757
Administrator
Superhero Member
*****
Posts: 3853



« Reply #351 on: March 30, 2009, 12:04:47 am »



   Don Joao de Castro Bank

Two unusual-looking flank craters are visible in this side-viewing sonar perspective of the NW flank of Don Joao de Castro Bank in the Azores taken by U.S. Navy submarine NR-1. The two craters are 90 x 45 m wide. The left-hand and younger crater displays a floor consisting of a chilled lava lake with polygonal surface fractures. The right-hand crater is much less distinct because its surface is obscured by tephra deposits. The line at the right is the center track line of the sonar image.

U. S. Navy image courtesy of Rick Wunderman, 2003 (Smithsonian Institution).

Country: Portugal
Subregion Name: Azores and Madeira
Volcano Number: 1802-07=
Volcano Type: Submarine volcano
Volcano Status: Historical
Last Known Eruption: 1720   
Summit Elevation: -14 m - 46 feet
Latitude: 38.23°N  38°14'0"N
Longitude: 26.63°W 26°38'0"W
Don Joao de Castro Bank is a large submarine volcano that rises to within 14 m of the sea surface roughly halfway between Terceira and San Miguel Islands. A submarine eruption during December 1720 produced an ephemeral island that attained a length of 1.5 km and an altitude of about 250 m before it was eroded beneath the sea surface two years later. The volcano (also spelled Dom Joao de Castro) was named after the Portuguese hydrographic survey vessel that surveyed the bank in 1941. Two youthful parasitic craters, one tephra covered and the other sediment free, are located on the NW flank. The submarine volcano has an impressive fumarole field and remains seismically active. 
Report Spam   Logged
dhill757
Administrator
Superhero Member
*****
Posts: 3853



« Reply #352 on: March 30, 2009, 12:05:19 am »



   Sete Cidades


A small peninsula juts into Lagoa Azul ("Blue Lake"), one of two lakes partially filling the summit caldera on Sete Cidades volcano at the western end of Sao Miguel Island. The 5-km-wide caldera was formed about 22,000 years ago, and at least 22 post-caldera eruptions have occurred. This view looks to the NW from the rim of a post-caldera cone, Caldiera Grande. Two other post-caldera cones, Caldiera do Alfreres and Seara Cerrado da Ladeira, lie across the lake, behind and to the right of the town of Sete Cidades.

Photo by R.V. Fisher, 1980 (University of California Santa Barbara).



 Country: Portugal
Subregion Name: Azores and Madeira
Volcano Number: 1802-08=
Volcano Type: Stratovolcano
Volcano Status: Historical
Last Known Eruption: 1880   
Summit Elevation: 856 m 2,808 feet
Latitude: 37.87°N  37°52'0"N
Longitude: 25.78°W 25°47'0"W
Sete Cidades volcano at the western end of Sao Miguel Island contains a 5-km-wide summit caldera, occupied by two caldera lakes, that is one of the scenic highlights of the Azores. The steep-walled, 500-m-deep caldera was formed about 22,000 years ago, and at least 22 post-caldera eruptions have occurred. A large group of Pleistocene post-caldera trachytic lava domes, lava flows, and pyroclastic-flow deposits is found on the western-to-northern flanks. A nearly circular ring of six Holocene pyroclastic cones occupies the caldera floor. These have been the source of a dozen trachytic pumice-fall deposits erupted during the past 5000 years. Sete Cidades is one of the most active Azorean volcanoes. Historical eruptions date back to the 15th century and have occurred from within the caldera and from submarine vents off the west coast. 
Report Spam   Logged
dhill757
Administrator
Superhero Member
*****
Posts: 3853



« Reply #353 on: March 30, 2009, 12:05:50 am »



   Unnamed   

A chain of fissure-fed scoria cones dotting the "waist" of Sao Miguel Island between Sete Cidades and Agua de Pau volcanoes is seen here from the east below the Agua de Pau (Lagoa do Fogo) caldera. The densely populated southern coast of Sao Miguel appears in the background. At least 18 eruptions have occurred during the past 2800 years, although the only historical eruption took place in 1652 from a vent along the axis of the island.

Copyrighted photo by Marco Fulle, 2000 (Stromboli On-Line, http://stromboli.net).



 Country: Portugal
Subregion Name: Azores and Madeira
Volcano Number: 1802-081
Volcano Type: Pyroclastic cones
Volcano Status: Historical
Last Known Eruption: 1652   
Summit Elevation: 350 m 1,148 feet
Latitude: 37.78°N * 37°47'0"N
Longitude: 25.67°W 25°40'0"W
Nearly 200 scoria cones dot the "waist" of Sao Miguel Island between Sete Cidades and Agua de Pau volcanoes. This monogenetic fissure-controlled, dominantly basaltic volcanism, much of which post-dates the roughly 5000-year-old Fogo eruption, cannot be assigned to either volcano and appears related to en-echelon fissures overlying a fracture zone. Thick pumice deposits thought to originate from the "waist" area may have originated from vents or a caldera destroyed and now buried by young basaltic volcanism. The most noteworthy of the young vents is 485-m-high Serra Gorda, SE of Siete Cidades, and the cone that produced a lava delta south of Agua de Paul village. The majority of the inhabitants of Sao Miguel Island occupy both coasts below this volcanic zone. At least 18 eruptions have occurred during the past 2800 years, although the only historical eruption occurred in 1652. The most recent activity has been basaltic, however two more-explosive trachytic eruptions occurred during the past 1100 years.
Report Spam   Logged
dhill757
Administrator
Superhero Member
*****
Posts: 3853



« Reply #354 on: March 30, 2009, 12:06:26 am »



   Agua de Pau  


Lagoa do Fogo lake, seen here from the west, partially fills the younger of two Pleistocene calderas on Agua de Pau stratovolcano in central Sao Miguel Island. Several post-caldera lava domes were emplaced on the northern and western flanks of the volcano, but activity inside the caldera did not resume until the eruption of the 5000-year-old Fogo-A plinian pumice-fall deposit, the product of the largest-known Holocene eruption in the Azores. Numerous cinder cones have erupted on the flanks of Agua de Pau during historical time.

Photo by Rick Wunderman, 1977 (Smithsonian Institution).


 Country: Portugal
Subregion Name: Azores and Madeira
Volcano Number: 1802-09=
Volcano Type: Stratovolcano
Volcano Status: Historical
Last Known Eruption: 1564   
Summit Elevation: 947 m 3,107 feet
Latitude: 37.77°N  37°46'0"N
Longitude: 25.47°W 25°28'0"W
Agua de Pau stratovolcano in central Sao Miguel Island contains an outer 4 x 7 km caldera formed about 30,000 to 45,000 years ago and an inner 2.5 x 3 km caldera that was created about 15,000 years ago. The younger caldera is partially filled by the Lagoa do Fogo caldera lake. Several post-caldera lava domes were emplaced on the northern and western flanks of the volcano, but activity in the caldera did not resume until about 5000 years ago. The 3-cu-km Fogo-A plinian pumice-fall deposit, the product of the largest-known Holocene eruption in the Azores, was emplaced at this time. Numerous flank cinder cones mark radial and concentric fissures, some of which have been active during historical time. The latest trachytic explosive eruption took place during 1563. Prominent hot springs are located on the NW flank.
Report Spam   Logged
dhill757
Administrator
Superhero Member
*****
Posts: 3853



« Reply #355 on: March 30, 2009, 12:07:03 am »



   Furnas

Furnas volcano, at the eastern end of Sao Miguel Island, contains at least two calderas. The younger 6-km-wide caldera is seen here from its northern rim. At least 11 trachytic pumice layers, all erupted during the past 5000 years, post-date the caldera. A zone of late-Pleistocene to Holocene basaltic-to-trachytic cinder cones and lava domes is located between Furnas and neighboring Agua de Pau volcano. The only historical eruption of Furnas volcano, during 1630, was one of the largest Holocene eruptions in the Azores.

Photo by Rick Wunderman, 1997 (Smithsonian Institution).



 Country: Portugal
Subregion Name: Azores and Madeira
Volcano Number: 1802-10=
Volcano Type: Stratovolcano
Volcano Status: Historical
Last Known Eruption: 1630   
Summit Elevation: 805 m 2,641 feet
Latitude: 37.77°N  37°46'0"N
Longitude: 25.32°W 25°19'0"W
Furnas volcano lies at the eastern end of Sao Miguel Island, immediately west of the older Nordeste shield volcano and its Povoaçao caldera. Furnas contains at least two calderas, a younger one that is 6-km wide and a larger older one that is less topographically distinct. The eastern wall of the 500-m-deep caldera of Furnas overlaps the western wall of the Povoaçao caldera of Nordeste volcano. Volcanic activity at Furnas dates back about 100,000 years. At least 11 trachytic pumice layers, all erupted during the past 5000 years, post-date the caldera. The most prominent post-caldera feature is the Pico do Gaspar lava dome, east of the Lagoa das Furnas caldera lake. A zone of late-Pleistocene to Holocene basaltic-to-trachytic cinder cones and lava domes is located between Furnas and Agua de Pau volcanoes. Two historical eruptions have occurred at Furnas, one sometime between 1439 and 1443 and the other in 1630. The latter was one of the largest Holocene explosive eruptions in the Azores and caused significant damage and fatalities.
Report Spam   Logged
dhill757
Administrator
Superhero Member
*****
Posts: 3853



« Reply #356 on: March 30, 2009, 12:07:52 am »

   Monaco Bank 

A photograph is not available for this volcano.
 Country: Portugal
Subregion Name: Azores and Madeira
Volcano Number: 1802-11=
Volcano Type: Submarine volcano
Volcano Status: Historical
Last Known Eruption: 1911   
Summit Elevation: -197 m - 646 feet
Latitude: 37.60°N  37°36'0"N
Longitude: 25.88°W 25°53'0"W
Monaco Bank is a submarine volcano constructed along a NW-SE-trending fissure 20-km south of the western tip of Sao Miguel Island. The linear volcano is located along regional tectonic trends connecting Sete Cidades volcano with Santa María Island, SE of Monaco Bank. The summit of the volcano rises to within 197 m of the sea surface. Submarine eruptions took place during 1907, when a submarine cable was ruptured, and 1911.
Report Spam   Logged
dhill757
Administrator
Superhero Member
*****
Posts: 3853



« Reply #357 on: March 30, 2009, 12:09:01 am »



   Madeira

Funchal, the capital city of Madeira, blankets the SE flanks of the massive shield volcano forming the island. The scenic island, sometimes known as the Pearl of the Atlantic, is the emergent summit of a volcano constructed along an East-West trending rift zone. Following a period of extensive erosion, renewed eruptions produced cinder cones and lava flows that traveled down dissected valleys.

Photo by Paul Bernhardt.



Country: Portugal
Subregion Name: Azores and Madeira
Volcano Number: 1802-12-
Volcano Type: Shield volcano
Volcano Status: Radiocarbon
Last Known Eruption: 4500 BC ± 50 years 
Summit Elevation: 1862 m 6,109 feet
Latitude: 32.73°N  32°44'0"N
Longitude: 16.97°W 16°58'0"W
Madeira Island is the emergent top of a massive shield volcano that rises about 6 km from the floor of the Atlantic Ocean and forms the largest island of the Madeira Archipelago, about 90 km in length. Construction of the volcano along E-W-trending rift zones from the Miocene to about 700,000 years ago was followed by a period of extensive erosion and possible edifice collapse. Two steep-walled amphitheaters open to south in the central part of the island. Late-stage eruptions are scattered throughout the island and lasted until the Holocene, producing scoria cones and intracanyon lava flows mantling rocks of the older eroded edifice. The youngest activity at Madeira lies in the west-central part of the island, and consists of cinder cones in the upper Sao Vicente valley, a series of intracanyon flows, and a tephra layer on top of the Paul da Serra plateau dated at about 6500 years ago.


http://www.volcano.si.edu/world/region.cfm?rnum=1802
Report Spam   Logged
dhill757
Administrator
Superhero Member
*****
Posts: 3853



« Reply #358 on: March 30, 2009, 12:10:31 am »


La Palma

The northern of two large volcanic centers forming the wedge-shaped island of La Palma, Taburiente, is seen from the southern volcano, Cumbre Vieja. Bejenado volcano (left-center) is located in the large breached caldera of Taburiente volcano (background). Cumbre Nueva Ridge (right) was formed by a large-scale collapse. Cumbre Vieja, the southern volcano, is one of the most active in the Canaries. The elongated volcano is oriented N-S and has been the site of numerous historical eruptions.

Photo by Yasuo Miyabuchi, 1997 (Forestry and Forest Products Research Institute, Kyushu).

 Country: Spain
Subregion Name: Canary Islands
Volcano Number: 1803-01-
Volcano Type: Stratovolcanoes
Volcano Status: Historical
Last Known Eruption: 1971   
Summit Elevation: 2426 m 7,959 feet
Latitude: 28.57°N  28°34'0"N
Longitude: 17.83°W 17°50'0"W


The 47-km-long wedge-shaped island of La Palma, the NW-most of the Canary Islands, is composed of two large volcanic centers. The older 2426-m-high northern one is cut by the massive steep-walled Caldera Taburiente, one of several massive collapse scarps produced by edifice failure to the SW. The younger 1949-m-high Cumbre Vieja, the southern volcano, is one of the most active in the Canaries. The elongated volcano dates back to about 125,000 years ago and is oriented N-S. Eruptions during the past 7000 years have originated from the abundant cinder cones and craters along the axis of Cumbre Vieja, producing fissure-fed lava flows that descend steeply to the sea. Historical eruptions at La Palma, recorded since the 15th century, have produced mild explosive activity and lava flows that damaged populated areas. The southern tip of the island is mantled by a broad lava field produced during the 1677-1678 eruption. Lava flows also reached the sea in 1585, 1646, 1712, 1949, and 1971.

http://www.volcano.si.edu/world/volcano.cfm?vnum=1803-01-
Report Spam   Logged
dhill757
Administrator
Superhero Member
*****
Posts: 3853



« Reply #359 on: March 30, 2009, 12:11:27 am »



Hierro

The massive Hierro shield volcano is truncated by a large NW-facing escarpment, seen here from the east, which formed as a result of gravitational collapse of the volcano. The steep-sided 1500-m-high scarp towers above a low lava platform bordering 12-km-wide El Golfo Bay, which is barely visible at the extreme left. Holocene cones and flows are found both on the outer flanks and in the El Golfo depression. The latest eruption, during the 18th century, produced a lava flow from a cinder cone on the NW side of El Golfo.

Photo by Yasuo Miyabuchi, 1997 (Forestry and Forest Products Research Institute, Kyushu).

 
 Country: Spain
Subregion Name: Canary Islands
Volcano Number: 1803-02-
Volcano Type: Shield volcano
Volcano Status: Radiocarbon
Last Known Eruption: 550 BC ± 75 years 
Summit Elevation: 1500 m 4,921 feet
Latitude: 27.73°N  27°44'0"N
Longitude: 18.03°W 18°2'0"W


The triangular island of Hierro is the SW-most and least studied of the Canary Islands. The massive Hierro shield volcano is truncated by a large NW-facing escarpment formed as a result of gravitational collapse of El Golfo volcano about 130,000 years ago. The steep-sided 1500-m-high scarp towers above a low lava platform bordering 12-km-wide El Golfo Bay, and three other large submarine landslide deposits occur to the SW and SE. Three prominent rifts oriented NW, NE, and south at 120 degree angles form prominent topographic ridges. The subaerial portion of the volcano consists of flat-lying Quaternary basaltic and trachybasaltic lava flows and tuffs capped by numerous young cinder cones and lava flows. Holocene cones and flows are found both on the outer flanks and in the El Golfo depression. Hierro contains the greatest concentration of young vents in the Canary Islands. Uncertainty surrounds the report of an historical eruption in 1793. 

Report Spam   Logged
Pages: 1 ... 18 19 20 21 22 23 [24] 25   Go Up
  Print  
 
Jump to:  

Powered by EzPortal
Bookmark this site! | Upgrade This Forum
SMF For Free - Create your own Forum | Buy traffic for your forum/website
Powered by SMF | SMF © 2016, Simple Machines