USGS/Cascades Volcano Observatory, Vancouver, Washington
DESCRIPTION:
Lava Lakes
- Lava Lakes
- Africa
- Erebus (Antarctica)
- Erta Ale (Ethiopia)
- Kilauea (Hawaii)
- Nyamuragira (D.R. of the Congo)
- Tongariro (New Zealand)
From:
USGS Volcano Hazards Program Website, 2003
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Lava lakes are large volumes of molten lava,
usually basaltic, contained in a vent, crater, or
broad depression. Scientists use the term to
describe both lava lakes that are molten and
those that are partly or completely solidified.
Lava lakes can form (1) from one or more
vents in a crater that erupts enough lava to
partially fill the crater; (2) when lava pours into
a crater or broad depression and partially fills
the crater; and (3) atop a new vent that erupts
lava continuously for a period of several
weeks or more and slowly builds a crater
higher and higher above the surrounding
ground.
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Active lava lakes typically consist of a
partially solidified shiny gray crust
because its surface is constantly cooled by the
atmosphere. The crust is seldom more than
5-30 centimeters thick, or more than a few
minutes or hours old, because the crust
continually circulates, breaks, and sinks
into the moving molten lava below. T
he pattern of movement on the surface of
lava lakes is often compared to the type of
large-scale movement that occurs between
the huge plates that make up the
Earth's crust, including subduction, spreading,
and strike-slip movement.
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Lava lakes occur at relatively few volcanoes in the world.
For example, since 1980, lava lakes have formed at
Kilauea Volcano in Hawaii,
Mount Erebus in Antarctica
(involving rare phonolitic lava),
Erta Ale in Ethiopia and
Nyiragongo in
the Democratic Republic of the Congo.
From:
Tilling, Heliker, and Wright, 1987, Eruptions of Hawaiian Volcanoes:
Past, Present, and Future: USGS General Interest Publication, 54p.
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Another common lava product is the ponded flow or lava lake ...
The surface of lava that is ponded is smooth, broken only by polygonal cooling
cracks, formed in much the same way as shrinkage cracks in mud that has been
dried by the sun.
From:
Simkin and Siebert, 1994, Volcanoes of the World
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Africa
leads the world in lava lake production, with 9 percent of its eruptions -- all at
Nyiragongo and
Erta Ale
- having exhibited this uncommon characteristic.
-
Africa Volcanoes and Volcanics Menu
From: Smithsonian Institution Global Volcanism Program Website, 2001
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Mount Erebus (3,794 meters), the world's southernmost historically
active volcano, overlooks the McMurdo
research station on Ross Island.
Erebus is the largest of three major volcanoes forming the crudely triangular Ross
Island. The summit has been modified by
several generations of caldera formation. A summit plateau at about 3,200
meters altitude marks the rim of the
youngest caldera, within which the modern cone was constructed. An elliptical 500 x
600 meter wide, 110-meter-deep crater
truncates the summit and contains an active lava lake within a 250-meter-wide,
100-meter-deep inner crater.
The glacier-covered volcano was erupting when first sighted by Captain James Ross in
1841. Continuous lava-lake activity has
been documented since 1972, punctuated by occasional strombolian explosions
that eject bombs onto the crater rim.
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Antarctica Volcanoes and Volcanics Menu
From: Smithsonian Institution Global Volcanism Program Website, 2003
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Erta Ale
is an isolated basaltic
shield volcano
that is the most active volcano in
Ethiopia.
The broad, 50-kilometer-wide
volcano rises more than 600 meters from below sea
level in the barren Danakil depression. Erta Ale is the namesake
and most prominent feature of the Erta Ale Range.
The 613-meter-high volcano contains a 0.7 x 1.6 kilometers,
elliptical summit crater housing steep-sided pit craters.
Another larger 1.8 x 3.1 kilometer-wide depression elongated
parallel to the trend of the Erta Ale range is located to
the southeast of the summit and is bounded by curvilinear fault
scarps on the southeast side. Fresh-looking basaltic
lava flows from these fissures have poured into the
caldera
and
locally oveflowed its rim.
The summit caldera is renowned
for one, or sometimes two longterm lava lakes that have been
active since at least 1967, or possibly since 1906.
Recent
fissure eruptions have occurred on the northern flank of Erta
Ale.
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Africa Volcanoes and Volcanics Menu
From:
Smithsonian Institution Global Volcanism Website, 2003
-
Kilauea volcano, which overlaps the east flank of the massive
Mauna Loa shield volcano, has been
Hawaii's most active
volcano during historical time.
Eruptions of Kilauea are prominent in Polynesian legends;
written documentation extending back
to only 1820 records frequent summit and flank
lava flow eruptions that were interspersed with periods of
long-term lava lake
activity that lasted until 1924 at Halemaumau crater, within the summit caldera.
The 3 x 5 kilometer caldera was formed in several
stages about 1,500 years ago and during the 18th century;
eruptions have also originated from the lengthy east and SW rift
zones, which extend to the sea on both sides of the volcano.
About 90 percent of the surface of Kilauea is formed of lava flows less
than about 1,100 years old; 70 percent of the volcano's surface
is younger than 600 years. A longterm eruption that began in 1983 has
produced lava flows covering more than 100 square kilometers
and has destroyed nearly 200 houses. Intensive monitoring and field
research by staff of the Hawaiian Volcano Observatory,
established in 1912, make Kilauea one of Earth's best studied
volcanoes.
From:
Hawaii Volcano Observatory Website, 2003
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Nearly continuous lava-lake activity
on the caldera floor characterized the period from before
1823 until 1924.
From: Smithsonian Institution Global Volcanism Program Website, 2002
-
Africa's
most active volcano, Nyamuragira
is a massive basaltic shield volcano that rises north of Lake Kivu across a
broad valley northwest of Nyiragongo volcano.
The volcano has a volume of 500 cubic kilometers and extensive lava
flows from Nyamuragira cover 1,500 square kilometers of the East African Rift.
The 3,058-meter-high summit is truncated
by a small 2 x 2.3 kilometer summit caldera that has walls
up to about 100 meters high. Historical eruptions have
occurred within the summit caldera, frequently modifying the
morphology of the caldera floor, as well as from the
numerous fissures and cinder cones on the volcano's flanks.
A lava lake in the summit crater, active since at least 1921,
drained in 1938.
Twentieth-century lava flows extend down the flanks more
than 30 kilometers from the summit, reaching as far
as Lake Kivu.
-
Africa Volcanoes and Volcanics Menu
From:
Smithsonian Institution Global Volcanism Program Website, 2003
-
Tongariro (New Zealand)
is a large
andesitic volcanic massif,
located immediately northeast of Ruapehu volcano, that is
composed of more than a dozen composite cones
constructed over a period of 275,000 years. Vents
along a northeast-trending zone extending from
Saddle Cone (below Ruapehu volcano) to Te Mari crater
(including vents at the present-day location of Ngauruhoe)
were active during a several hundred year
long period around 10,000 years ago, producing the
largest known eruptions at the Tongarioro complex
during the Holocene.
North Crater stratovolcano,
one of the largest features of the massif, is truncated by
a broad, shallow crater filled by a
solidified lava lake
that is cut on the northwest side by a small explosion
crater. The youngest cone of the complex,
Ngauruhoe, has grown to become the highest peak of the
massif since its birth about 2,500 years ago.
The symmetrical, steep-sided Ngauruhoe, along with its
neighbor Ruapehu to the south, have been
New Zealand's most active volcanoes during historical time.
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New Zealand Volcanoes and Volcanics Menu
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02/06/03, Lyn Topinka