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Alcedo

Alcedo

Alcedo is one of the lowest and smallest of six shield volcanoes on Isabela Island. Seen here from coast of Fernandina Island to its west, Alcedo has a broad 7-8 km wide summit caldera. Most of the flanks and summit caldera are vegetated, but young lava flows are prominent on the northern flank near the saddle with Darwin volcano. Alcedo is the only Galapagos volcano known to have erupted rhyolite as well as basalt. Only one eruption is known during historical time. An active hydrothermal system is located within the caldera.

Auckland Field

Auckland Field

Rangitoto shield volcano, the youngest volcanic center of New Zealand's Auckland volcanic field, forms a 5.5-km-wide island. The volcano, seen here from the NW, erupted about 600 years ago and is capped by a scoria cone containing a deep crater. The 140 sq km Auckland volcanic field contains more than 50 maars, tuff rings, and scoria cones. Of the 19 eruptions known to have occurred during the past 20,000 years, only Rangitoto has erupted during the Holocene.

Belknap

Belknap

Little Belknap (upper left) is an example of a small shield volcano in a continental margin setting. Little Belknap was constructed on the east flank of Belknap volcano and spread fresh-looking lava flows over the McKenzie Pass area of the central Oregon Cascades about 2900 years ago. Collapsed lava tubes that fed the flows diverge radially away from the summit. The summit pinnacle of Mount Washington appears at the right beyond the Little Belknap lava apron.

Darwin

Darwin

Volcan Darwin, named after the celebrated naturalist, rises above a narrow channel opposite Point Espinosa on the NE tip of Fernandina Island. Darwin volcano contains a symmetrical 5-km-wide summit caldera that is nearly filled by lava flows. The most recent summit activity produced several small lava flows from vents on the east caldera floor and NE and SE caldera rims. Two breached tuff cones on the SW-flank coast, Tagus and Beagle, were a prominent part of Darwin's geological studies in the Galapagos Islands.

Fernandina

Fernandina

Fernandina volcano displays the classic overturned soupbowl profile of Galapagos volcanoes. Steep upper flanks formed by eruptions of lava flows from circumferential fissures around a summit caldera rim contrast with the broad, low-angle lower flanks and horizontal flows around the summit. Scientists from the Smithsonian Institution, U.S. Geological Survey, and the Charles Darwin Research Station conduct measurements on a pahoehoe lava flow near the SE coast. Vast fields of fresh, unvegetated lava flows cover the volcano's flanks.

Fremrinamur

Fremrinamur

Fremrinamur central volcano, NNE of Askja and SE of Myvatn lake, is a volcanic system that is being constructed over the Ketildyngja shield volcano (center). Associated fissure systems, including the Sveinar fissure, extend 130 km to the northern coast of Iceland. Iceland's renowned Myvatn lake formed as a result of the eruption of the massive 70-km-long older Laxarhraun lava flow from Ketildyngja shield volcano about 3800 years ago. The latest eruption from Fremrinamur produced the Burfellshraun lava flow about 2500-3000 years ago.

Hualalai

Hualalai

Hualalai shield volcano, seen here from the SE at the summit of Mauna Loa, rises to 2523 m. Almost the entire surface of Hualalai is covered by lava flows of Holocene age. Unlike Mauna Loa, Hualalai has been relatively inactive during historical time. It's only historical eruption took place in 1800-01, when lava flows from two vents on the NW rift zone reached the sea. This eruption was of particular volcanological interest because of the large numbers of olivine-rich nodules that were brought to the surface by the lava flows.

Mauna Kea

Mauna Kea

Mauna Kea, Hawaii's highest volcano, is seen here from the south at the broad Humuulu Saddle between Mauna Kea and Mauna Loa. The fresh lava flow in the foreground was emplaced during an 1843 eruption that originated on the NE rift zone of Mauna Loa. The flow traveled directly north to the Mauna Kea saddle, where it was deflected to the west. The irregular profile of the unvegetated summit region of Mauna Kea shield volcano is produced by a cap of cinder cones and pyroclastic ejecta that is not present at Mauna Loa.

Mauna Kea

Mauna Kea

Hawaii's two largest shield volcanoes, Mauna Loa (in the background to the south) and Mauna Kea, have dramatically differing profiles. Mauna Loa, the world's largest active volcano, has the classic low-angle profile of a shield volcano constructed by repetitive eruptions of thin, overlapping lava flows. Mauna Kea is also a shield volcano formed in the same manner, but its profile has been modified by late-stage explosive eruptions, which constructed a series of cinder cones that cap its summit.

Mauna Kea

Mauna Kea

Mauna Kea (left) and Mauna Loa (right), both over 4000 m above sea level, are the world's largest active volcanoes, rising nearly 9 km above the sea floor around the island of Hawaii. This aerial view from the NW shows the contrasting morphologies of these two shield volcanoes. In contrast to the smooth profile of Mauna Loa, Mauna Kea's early shield volcano morphology is modified by the late-stage products of explosive eruptions.

Mauna Loa

Mauna Loa

The steep walls of Lua Poholo pit crater, immediately NE of Mokuaweoweo caldera, expose a small portion of the massive pile of thin, overlapping lava flows that have construced the Mauna Loa shield volcano. This view from the NE shows the rim of Mokuaweoweo caldera at the upper right. Lava flows from recent eruptions, including the last eruption of Mauna Loa, in 1984, fill the floor of the pit crater.

Mauna Loa

Mauna Loa

Hawaii's two largest shield volcanoes, Mauna Loa (in the background to the south) and Mauna Kea, have dramatically differing profiles. Mauna Loa, the world's largest active volcano, has the classic low-angle profile of a shield volcano constructed by repetitive eruptions of thin, overlapping lava flows. Mauna Kea is also a shield volcano formed in the same manner, but its profile has been modified by late-stage explosive eruptions, which constructed a series of cinder cones that cap its summit.

Mauna Loa

Mauna Loa

Mauna Kea (left) and Mauna Loa (right), both over 4000 m above sea level, are the world's largest active volcanoes, rising nearly 9 km above the sea floor around the island of Hawaii. This aerial view from the NW shows the contrasting morphologies of these two shield volcanoes. In contrast to the smooth profile of Mauna Loa, Mauna Kea's early shield volcano morphology is modified by the late-stage products of explosive eruptions.

Newberry Volcano

Newberry Volcano

Massive Newberry shield volcano covers an area of about 1600 sq km about 60 km east of the crest of the Cascade Range in central Oregon. The elongated, low-angle shield volcano covers an area of 60 km in a N-S direction and 30 km E-W. More than 400 cinder cones dot the flanks of Newberry volcano, including Lava Butte cinder cone at the left center of this photo, one of many cones formed around 6100 years ago along the NW rift zone.

Prestahnukur

Prestahnukur

The classic Icelandic volcano Skjaldbreidur is perhaps the best known of the many small shield volcanoes that were constructed along rift zones where the Mid-Atlantic Ridge rises above sea level. Skjaldbreidur, seen here from the west along route 52, was formed about 9500 years ago during a single long-duration eruption at the southern end of the Prestahnukur volcanic system in central Iceland. The broad, low-angle shield volcano produced 17 cu km of basaltic lava flows and is capped by a small 300-m-wide summit crater.

San Quintin Volc Field

San Quintin Volc Field

Isla San Martin, 6 km off the west coast of Baja California, is the westernmost volcano of the San Quintin volcanic field and the only one that is located offshore. The 2-km-wide island is a small basaltic shield volcano that is capped by scoria cones that rise to 230 m above sea level. Wave erosion has truncated part of the shield volcano, forming the sea cliffs seen at the left on the south side of the island.

Wolf

Wolf

Wolf, the highest volcano of the Galapagos Islands, straddles the equator at the north end of the archipelago's largest island, Isabela. Volcan Wolf shield volcano has steeper slopes than most other Isabela volcanoes. A 5.5 x 7 km caldera, 600 m deep, is located at the volcano's summit. The broad caldera floor is largely covered by fresh, unvegetated lava flows. Prominent unvegetated lava flows drape forested eastern flanks of the volcano to the sea. Wolf's 1797 eruption was the first documented in the Galapagos Islands.


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