Transcript Hawaii Volcanoes

Volcanoes of the Island of Hawaii
Seven Shield Volcanoes
Types of Volcanoes
Descriptions and Images
Eruption
Mahukona
Loihi
How and why volcanoes erupt
GG103
Nasir Gadzar
5 Shield Volcanoes
2 Submarine cones
Red – recent volcanism
on the ocean floor
Green – Hawaiian islands
Hawaiian Islands
Pacific Ocean
Island of Hawaii
The subaerial (rocky,
above sea level) portion
of the Island of Hawaii is
made of five volcanoes. Mahukona
From oldest to youngest,
they are Kohala, Mauna
Kea, Hualalai, Mauna
Loa, and Kilauea. Each
volcano can be
recognized by its size,
shape, and physical
features. Two other
volcanoes, Mahukona
Pacific Ocean
and Loihi, add to the
submarine base of the
Island.
Volcanoes of the Island of Hawaii, elevation, area.
Volcanoes are classified as:
Active - These are erupting
or keep erupting. Kilauea
Dormant - These are not
erupting but could at any
time. Mauna Kea
Extinct - These volcanoes are
no longer active and do not
erupt. Diamond Head Crater
~1500 volcanoes are potentially actives on Earth
􀀹 ~ 70 are currently in eruption
􀀹 ~ 10% of the human population is directly exposed
to volcanic risk. Several large cities are located close
to an active or dormant volcano
􀀹
Cinder Cones - Cinder cones are the
simplest type of volcano. They are built
from particles and blobs of congealed lava
ejected from a single vent. As the gascharged lava is blown violently into the
air, it breaks into small fragments that
solidify and fall as cinders around the vent
to form a circular or oval cone. Most
cinder cones have a bowl-shaped crater at
the summit and rarely rise more than a
thousand feet or so above their
surroundings. Cinder cones are numerous
in Hawaii as well as throughout other
volcanic terrains of the world.
Shields - Another easily recognized volcano which is
familiar is the Shield volcano. This type of volcano
can be hundreds of miles across and many tens of
thousands of feet high. The individual islands of the
state of Hawaii are simply large shield volcanoes.
Mauna Loa, a shield volcano on the island of Hawaii,
is the largest single mountain in the world, rising over
30,000 feet above the ocean floor and reaching almost
100 miles across at its base. Shield volcanoes have
low slopes and consist almost entirely of frozen lavas
The animation shows the steps in the formation of a
caldera. The volcano usually shows signs of
erupting by producing earthquakes as the magma
rises in the volcano.
Calderas - Calderas, are simply circular depressions, are
found on the summits of many volcanoes. "Giant" calderas are
the largest of these: huge craters up to many tens of miles
across. Giant Calderas form by collapse (see animation) in
gigantic eruptions that spew volcanic rocks out hundreds or
even a thousand miles in all directions. Sometimes the
calderas are so filled with lava and volcanic ash that there is
no recognizable depression at all.
After a huge ejection of lava there may be no magma
left in the chamber to fill the conduit and crater. When
this happens there is a hollow space under the summit
of the mountain where the magma used to be. The top
of the mountain then collapses creating a caldera.
The caldera may fill with water creating a lake.
Shield Volcanoes of the Hawaiian Islands
Shield Volcanoes are enormous features built up only from
layers of lava. They produce lots of A’a and Pahohoe lava
flows but they tend not to erupt violently.
Topographic Profile of Mauna Loa
Basaltic Lava Flow
10,000m
250 kilometer
Hawaiian Islands
Palaeogeographical
Location of the
various islands over
the active volcanic
activity (hotspot red
circle) at different
times
Kilauea magma hiding from volcano scientists: Scientists at Kilauea
Volcano are pondering the big question: Where is 250,000 cubic yards of
magma going if it's not flowing each day to the Pu'u 'O'o eruption?
Magma that forced its way into the upper East Rift Zone and caused
hundreds of earthquakes finally cracked the surface.
A tour boat had a sea view of lava from Kilauea flowing into
the ocean. Michael Marlin
Lava flows from Kilauea March 12, 2008
An abandoned pickup truck is engulfed
in flames after lava from Kilauea came
into contact with it.
A backyard swimming pool in the Royal Gardens area of the Big Island that was once filled
with water is now filled with lava from Kilauea.
Stages of Growth of Volcanoes in Hawaii, 500,000 years ago
In order of growth, the volcanoes that make the island and its submarine
base are Mahukona, Kohala, Mauna Kea, Hualalai, Mauna Loa,
Kilauea, and Loihi. Mahukona, Kohala, Mauna Kea, and Hualalai have
completed their shield-building stage.
Mahukona
slides into
the sea
The island has grown at an average rate of 0.008 mi2/yr (5 acres; 0.02
km2/yr) for the past 600,000 years. It is estimated that 600,000 years
was required for each volcano to grow from the ocean floor to the end of
its shield building stage
Kohala Shield Volcano – Extinct volcano
Most Recent Eruption(s)
About 120,000 years ago
Number of Historical Eruptions
none
Oldest Dated Rocks
Location
About 460,000 years before present
20.08 N 155.70 W
46 万年間
Elev. Above Sea
Estimated Age of Kohala
Emerged above sea level before 500,000 Level 1,670 m
5,480 ft
years ago
Area 606 km2
Hawaiian Volcano Stage
235 mi2
Transition between postshield and
(5.8% of Hawai`i)
erosional stage
Volume 14,000
km3, 3,400 cu mi3
Mauna Kea – tallest volcanoe
Most Recent Eruption(s)
At least 7 separate vents erupted between
about 6,000 and 4,000 years ago
Number of Historical Eruptions
none
Oldest Dated Rocks
237,000 ± 31,000 years before present
23 万年間
Estimated Age of Mauna Kea
About 1 million years, 100 万年間
Volcano Stage
Post-shield Stage (transition from shield
stage to post-shield occurred before about
200,000 to 250,000 years ago)
Location
19.82 N 155.47 W
Elev. Above Sea Level
4,205 m
13,796 ft
Area
2,380 km2
920 mi2
(22.8% of Hawai`i)
Volume
>30,000 km3
>7,200 mi3
Mauna Loa Most Recent Eruption, March 24-April
15, 1984
Summit Caldera Name: Moku`aweoweo, "Moku"
refers to a coastal land section or islet; "`aweoweo"
is a type of red Hawaiian fish. Literal translation is
fish section
Dimension: 3 x 5 km, elongated northeastsouthwest
Location
Depth: 183 m deep
19.475 N 155.608 W
Elev. Above Sea Level Age: estimated to have collapsed 600-750 years ago
Oldest Dated Rocks
4,170 m
13,680 ft
Between 100,000 and 200,000 years ago Estimated
Area
Age of Earliest Subaerial Eruptions
5,271 km2
About 400,000 years ago
2,035 mi2
Estimated Age of First Eruption of Mauna Loa
(50.5% of Hawai`i)
Between 1,000,000 and 700,000 years before
Volume
80,000 km3
present
19,000 mi3
Hawaiian Volcano Stage: Shield-forming stage
Hualalai: Most Recent Eruption(s) 1800 and 1801
Location
19.69 N
155.87 W
Elev. Above
Sea Level
2,521 m
8,271 ft
Area
751 km2
290 mi2
(7.2% of
Hawaii)
Volume
12,400 km3
2,975 mi3
Hawaiian Meaning The Hawaiian name "Kilauea" means
"spewing" or "much spreading," apparently in reference to the
lava flows that it erupts.
Most Recent Eruption
Continuous since January 3, 1983
Number of Historical Eruptions
61, not counting the continuous lava-lake activity in
Halema`uma`u crater
Summit Caldera The caldera itself has no Hawaiian name
other than Kilauea but houses the famous crater,
Halema`uma`u; "hale" is a house, "ma`uma`u" a type of fern.
Dimension: 6 x 6 km (outermost faults), 3 x 5 km (main
depression)
Depth: 165 m deep
Age: probably several incremental collapses 500-210 years ago
Oldest Dated Rocks
23,000 years old
Estimated Age of Earliest Subaerial Eruptions
50,000-100,000 years
Estimated Age of First Eruption of Kilauea
300,000-600,000 years before present
Hawaiian Volcano Stage Shield-forming stage
Location
19.425 N 155.292 W
Elev. Above Sea
Level
1,277 m
4,190 ft
Area
1,430 km2
552 mi2
(13.7% of Hawai`i)
Volume
25,000-35,000 km3
6,000-8,500 mi3
Loihi Seamount
depth = 969 meters
will reach surface in
about 30,000 years
Mahukona
Loihi
March 19, 2008 Explosive eruption in Halema`uma`u Crater, Kilauea
Volcano, is first since 1924
Volcanic gas escapes from a vent in the Halemaumau Crater near the Jaggar Museum inside
Hawaii Volcanoes National Park. AP Photo/Marco Garcia
The explosion scattered debris over an area of about 75 acres (30 hectares), covering a portion of
Crater Rim Drive and damaging the Halema‘uma‘u overlook. Rocks ejected by yesterday’s
explosion at Kilauea volcano dug impact craters when they hit. Finer-grained material was blown
away during the impact. Boulders and smaller rocks were scattered over a large area of Hawaii
Volcanoes National Park, but no one was injured. March 19,2008.
Kilauea: an explosive volcano in Hawai`i
Explosive eruptions at Kilauea are thought to be caused when water
comes into contact with hot or molten rock (magma) and flashes into
steam. In 1924, this happened after the level of the lava lake in
Halema'uma'u Crater dropped below the water table. The walls of the
crater then collapsed and blocked the opening down which the lava had
drained, allowing steam pressure to build up and cause violent explosions.
Many of Kilauea's pre-1924 explosive eruptions that produced
significant ash deposits probably happened when the volcano's summit
crater was so deep that its floor was below the water table, letting ground
water seep in to form a lake. Whenever magma erupted into the lake
water, violent explosions of steam and volcanic gases resulted,
fragmenting the magma into tiny ash particles and driving fast-moving,
extremely hot ash-laden steam clouds (pyroclastic surges) out of the
crater.
Kilauea eruption blasts rocks across
landscape March 19, 2008.
The most recent explosive eruptions
before March 19, 2008 were in 1924
and were much bigger than the latest
event. Those explosions killed a
photographer, who ventured too
close and was hit by falling rocks
and hot mud. This explosive
eruption at Kilauea on May 22,
1924, the cloud was 2 miles high
and still rising. Geologists now
believe such explosions were
common in the past
Rocks litter the area around a wooden fence at the Kilauea volcano
overlook. The fence was heavily damaged yesterday in the first explosive
eruption at Kilauea volcano in almost a century.
The largest boulder to be blasted out of Halemaumau Caldera was almost about 3› feet wide. It
landed on the steel cable of the barrier adjacent to the trail next to the Halemaumau Overlook.
The recent increase in hydrothermal or gas sources had forced the explosive eruption, the first
since May 1924. No lava was found in the area.
A near vertical view looks down into the explosion crater. The crater is estimated at roughly 100
feet across.
KAMEHAMEHA'S VOLCANIC VICTORY
The most significant Kilauea eruption ever
documented may have altered Hawai'i's history,
according to records at the Hawaiian Volcano
Observatory. Kamehameha I, before becoming
king and uniting the Islands, was locked in an
indecisive war with his rival, Keoua.
In 1790, a sudden eruption of searingly hot ash
and gas exploded out of Kilauea as a large group
of Keoua's warriors and their families passed
nearby. At least 80 and perhaps hundreds of
people were killed in the deadliest historical
eruption to occur in what is now the United
States. That disaster helped tip the rivalry in
Kamehameha's favor.
Pu'u 'O'o on Kilauea's East Rift
Zone has been producing about
2,000 metric tons of sulfur dioxide
a day for years, but only about 200
tons per day were being released at
Halema'uma'u at the summit.
That changed late last year when
sulfur dioxide emissions from the
summit began to climb, and by
March 13 had reached record levels
of 2,000 tons a day as a new vent
opened in the wall of the crater.
Debris avalanche
Debris avalanches are moving
masses of rock, soil and snow that
occur when the flank of a mountain
or volcano collapses and slides
downslope. As the moving debris
rushes down a volcano and into
river valleys, it incorporates water,
snow, trees, bridges, buildings, and
anything else in the way. Debris
avalanches may travel several
kilometers before coming to rest,
or they may transform into more
water-rich lahars, which travel
many tens of kilometers
downstream
Composition of Hawaiian Volcanoes
Igneous Rock
The term ``igneous'' comes from the Latin word ignis or
``fire''. Igneous rocks are rocks which form from cooling
magma or lava.
Magma
Molten or partially molten rock material and dissolved gases.
Magma is molten rock beneath Earth's surface.
Lava
Molten or partially molten rock material and dissolved gases.
Lava is molten rock which has erupted at Earth's surface.
Volcanic steam was rising yesterday from the MLK vent that has deepened on Kilauea
Hawaii Volcanoes National Park firefighter Sean Grossman, with hose, filled a 5,000-gallon "frog
pond" in the park June 21, 2007. The plastic pool was one of five set up by the park to have water
ready in case fire flares up from lava flows
Volcanic gases and vapors produce VOG - Volcanic fog,
LAZE- Lava haze, and acid rain. These air pollutants cause
health related problems, water pollution and damage to crops.
When sulfur dioxide concentrations greater than 1 ppm (equal
to 1,000 parts per billion) are measured, then the volcanic air
pollution is common.
Slump fissure at edge of Alae crater has split Chain of Craters Road. Kilauea east rift. Hawaii
Volcanoes National Park.
Giant landslides surrounding the Hawaiian Islands are among
the largest known on Earth, and most have occurred within the
past four million years. The youngest is thought to have
occurred only one hundred thousand years ago, and there is
evidence today that large blocks of land on the island of
Hawaii are beginning to slide, generating large earthquakes in
the process. Each slide has resulted in huge land losses to the
islands and resulted in large waves that have carried rocks and
sediments as high as 1000 ft above sea level. The giant
Hawaiian landslides are important to study because, although
they occur infrequently, they have potential for enormous loss
of life, property, and resources. Much of the existing
topography in Hawaii, both on land and on the seafloor, owes
its origin to these landslides,
Kilauea has been erupting nearly continuously since Jan. 3,
1983, sending lava from the Pu'u O'o cone through a system of
tubes to the ocean, where it forms new land over time.
In Hawaiian tradition, Kilauea is home to Pele, the volcano
goddess. Lava is said to be her physical representation
Kilauea Volcano:
'Something's got
to give' June 19, 2007
Watch Video at Honolulu
Advertiser
: Kilauea lava flows putting on
• What to know
about Kilauea • Kilauea's
showy display
recent activity hints at
eruption pattern
Magma pumping into Kilauea
volcano's upper East Rift Zone
has buried under lava or scorched
nearly seven acres of rainforest,
with heat and gases wilting and
sickening trees, ferns and other
plants around two large cracks
that opened this week as the rift
expanded
Magma Chamber is half filled….
Interior Tube
(After Harter & Harter, 1979)
(After Harter & Harter, 1979)
Surface Trench
(After Harter & Harter, 1979)
Semi Trench
(After Harter & Harter, 1979)
True Trench
Rift Tube - Pre-Flow
(After Macdonald, 1965)
Rift Tube - Flow 1
(After Macdonald, 1965)
Rift Tube - Flow 2
(After Macdonald, 1965)
Rift Tube - Flow 3
(After Macdonald, 1965)
Rift Tube - Flow 4
(After Macdonald, 1965)
Rift Tube - Flow 5
(After Macdonald, 1965)
Volcanic Lava Tube Forms
Kilauea "skylight" —
April 23, 2008 where a roof section
of a lava tube
collapsed — and then
poured into the
skylight, producing a
brief surface flow on
its way downslope to
the ocean.
Water Fills Tube
Lava flowing underground created this
lava
tube large enough to walk through.
_____ _____,
Volcanoes Review:
Fast-moving clouds of gas, ash, and other
pyroclastic
tephra are called ____________
_ flows
 Large, rounded tephra are called
__________
volcanic
bombs.
shield volcanoes.
 Iceland and Hawaii have ______
 A wall-shaped igneous intrusion is a
dike
______________.

There are three types of volcanic cones:
Cinder
cones – explosive eruptions, small but steep
• ______
slopes, pyroclastics
Shield – nonexplosive eruptions, fluid
• _______
basaltic lava, gentle broad slopes
Composite – alternating between lava and
• _________
pyroclastics, explosive and non-explosive
eruptions, steep and tall towering
shield
Kilauea on Hawaii is a good example of a _______
volcano, with some explosive eruptions and less
viscous lava.