Video Virtual Field Trip of Kilauea in Eruption
In many of our other Virtual Field Trips of Kilauea volcano, we have seen
geological features that have formed over the last 1,000 years. In our
research, we study the shape and distribution of lava flows, and measure
the temperature and the gases released from the on-going eruptions. As
visitors to Virtually Hawaii, what is missing from your experience of the
volcano is the movement of the lava and its effects as a flow enters the
ocean.
This Virtual Field Trip gives you that experience! Thanks to a
collaboration with other members of the University of Hawaii, we bring you a selection of volcano videos in this tour.
The Island of Hawaii is home to Kilauea volcano, the most active volcano on Earth.
The lava flows from Kilauea are derived from the Earth's mantle, approximately 60
kilometers below the surface. Lava flowing out of the Earth and into the sea is
the process that formed the Hawaiian Islands out of the great depths of the Pacific
Ocean, and which continues to enlarge the Big Island today.
Madame Pele is the Hawaiian volcano goddess, and she is perhaps at her most spectacular when she sends
her fiery red lava into the ocean. This film records the hidden beauty and drama
of this underwater encounter, where Pele meets the sea.
The latest phase of Kilauea's periodic eruptions started in January of 1983,
when towering fountains of molten lava built this cinder cone, Pu'u O'o. After
three years of activity, the fountaining finally stopped, but not before Pu'u O'o
had grown to a height of 130 meters. Since that time the flow of lava to Pu'u O'o
has continued, only now the lava travels in buried tubes down the mountain towards the sea.
Click here for movie.
Between 1989 and 1992, the main center of activity on the East Rift Zone of
Kilauea was at the Kupaianaha lava lake. While it was active, Kupaianaha
acted as a reservoir for the lava from Pu'u O'o before it headed down the
flank of the volcano. The size of the lava lake varied greatly from month
to month, as did the amount of molten lava it contained. Sometimes there
was enough lava to fill and overflow its steep walls.
This video shows a general view of the lava lake at a time when the level
was quite low, and gives us a good view of the start of three active lava
tubes on the downslope side of the lake. It is through these tubes that
the lava starts its 10 km journey to the ocean.
Click here for movie.
Magmatic gas was also released at Kupaianaha. The gas can be seen
as it churns the surface of the lava lake into fiery fountains, and also as
it bubbles gently to the surface.
Click here for movie.
At nighttime, the surface of the Kupaianaha lava lake is really impressive!
Parts of the solidified crust that are moving across the lake get
fractured and reveal molten lava just beneath the surface. This is similar
to the process of subduction of ocean floor via plate tectonics.
Here we can see in this video that the solid lake surface is denser than
the molten lava, and so sinks into the lake, causing new molten rock to
take its place on the surface.
Click here for movie.
The lava from Kupaianaha travels to the coast through a lava tube that may
be several meters in diameter and 1 to 5 meters beneath the surface. Often
the exact path is hard to tell from a distance, but you can always see
where the lava enters the ocean because of the giant steam plumes that the
lava creates. This video shows one such steam plume.
Click here for movie.
One of the best things to see on the volcano is the interaction between the
lava coming out of a lava tube and the ocean. Often there are small
explosions that hurl pieces of molten rock a few tens of meters into the
air. At other times, the lava is quenched in place.
This video shows the effects of surf on the moving lava flow. Notice how
much steam is produced, and how the lava is cooled for a few moments by
being drenched by the ocean.
Click here for movie.
The views of lava entering the ocean are even more spectacular at night.
The red hot lava glows off of the steam clouds that are created, so that
the entry points can be seen from miles away. Here we see the waves
beating on the lava as it leaves a lava tube (at the right in this
picture).
There are many other things that have been observed by University of Hawaii
scientists working just off-shore from the lava entry points. Here we have
a series of still photographs that show some of these phenomena, both on
the surface and underwater!
Floating rocks are frequently seen in the water in front of the shoreline
lava flows. They form from the spattering that occurs when the molten lava
touches the water. The resulting porous rocks are hot enough that sea
water entering them is instantly converted to steam, which keeps the rocks
buoyant. The floating rocks will sizzle and spin in the water for several
minutes, until they cool and eventually sink to the sea floor.
In order to see more of what is happening to the lava flows at the coast,
we have to put on scuba gear and go diving! As divers swim down to the
underwater flows, they frequently must deal with murky water filled with
small particles of volcanic glass.
Close to the active lava, our diver finds that pillow basalts form from
relatively slow moving submarine lava flows. This slow movement allows the
overlying seawater to rapidly cool the molten lava, which causes a surface
crust to quickly form, giving the resulting rock its distinctive pillow
shape. Large numbers of gas bubbles are released from the pillow basalts
while they form. These bubbles are distinctive in that they contain
relatively high levels of explosive hydrogen gas, which is formed by the
chemical reaction of sea water with the hot lava.
The formation of pillow lava underwater is accompanied by a steady stream
of sounds. Some are the result of fracturing of the cooling crust and the
implosion of the solid pillows. Other loud explosions result from the
combustion of hydrogen trapped under the cooled outer skin of the lava
flow.
It is also fascinating to see growing hot lava flows under water. Some of
the pillows observed at Kilauea are exceptionally fluid, and form long toes
such as the one seen here that have a central crack that propagates the
growing toe of incandescent lava.
It has been generally assumed by geologists that underwater lava flows
always produce pillows. However, at Kilauea we have seen other types of
underwater flows. These are fast-moving flows, similar to the channelized
lava flows observed on shore, and are fed by tubes that open directly onto
the seafloor.
The fracturing of cooling lava by the seawater results in the production of
large quantities of sharp glassy debris, ranging in size from fine
particles to small boulders. The bottom is very steep here, its slope
ranging from 30 to 45 degrees. As a result, there is a constant sliding of
bottom sediments down the slope, along with frequent slumping events which
transport large volumes of sediment, plus rocks and boulders, downslope.
Violent hydrogen explosions and jets of hot water can frequently be seen
along the larger active underwater flows below the mouth of the lava tube.
These explosions and hot springs are the results of sea water seeping down
into the seafloor and coming in contact with buried lava tubes. The
temperature of the jets is near the boiling point of water, as indicated by
the steam they vent. The jets are also another source of hydrogen-rich
bubbles.
In addition to having to contend with flowing red lava, underwater
explosions and landslides of razor-sharp lava rocks, the scuba divers have
one additional worry - floating lava rocks all eventually sink.
Diving and video movie: Richard Pyle, Jane Culp, Frank Sansone, Gordon
Tribble, Jane Tribble, David Schideler, Kevin Kelly, John Earle,
Randall Kosaki
Hydrophone sound track: 
