About 3 miles (4 km) down the
road is the side road to Mauna Ulu, a vent that was active from
1969-1974. The photograph here shows the mountain from a distance.
Below we'll cover a bit of the
history about this area so you'll be able to comprehend and
understand the complex history of this area when visiting it.
It's a pretty interesting geology lesson...
Prior to the Mauna Ulu eruption,
Chain of Craters Road continued east to Makaopuhi Crater and
down to the coast. It passed Aloi and Alae, two pit crater,
and Puu Huluhulu, a pre-historic cinder and spatter cone. The
Mauna Ulu eruption began on May 24, 1969.
The Mauna Ulu eruption ended
on July 22, 1974. Kilauea Volcano had erupted for nearly 5 years
at a vent on the East Rift Zone of the volcano. This was the
longest flank eruption of a Hawaiian volcano in historical time
(a record that has been broken by the current eruption). It
dramatically changed the landscape by covering large areas with
lava, filling two pit craters, constructing a new vent, and
adding land onto the island. See the diagrams below for a closer
detailed look.
The eruption began as a fissure
between Aloi and Alae pit craters. This area became the focus
of future activity that would construct the Mauna Ulu shield.
The early episodes of the Mauna Ulu eruption produced numerous
high lava fountains. Some of the fountains reached heights of
1,800 feet. Different phases of the eruption were separated
by pauses. During a pause, no lava was supplied to the vent.
The onset of the Mauna Ulu eruption was marked by 875 days of
nearly continuous activity. During this period, both Alae and
Aloi craters were filled with lava (see diagram above).
 The
steady supply of lava produced conditions that favored the development
of long lava tube systems. Tubes extended from Mauna Ulu to
the ocean, a distance of 6 miles. Skylights, holes in the tops
of tubes, provide volcanologists windows into the shallow plumbing
of the volcano. Measurements of the cross-sectional area of
the tube and the velocity of the lava provided an estimate of
the volume of lava erupted.
Lava entered the ocean and
added new land to the island at many different locations during
the course of the eruption. Following a six month hiatus in
eruption, activity resumed at Mauna Ulu in February 1972. Like
the previous period of continuous activity, lava traveled in
a tube from the lava lake at the summit of Mauna Ulu to a lava
lake at the location of Alae Crater. Overflows of this lava
lake built a second shield adjacent to Mauna Ulu. Unlike the
current eruption, where the active vent is in a remote location,
the vent for the Mauna Ulu eruption was accessible. Park visitors
could stand on the edge of the vent and peer into lake of lava.
 In
April of 1973, a magnitude 6.3 earthquake occurred on the island
of Hawaii. This earthquake apparently caused changes in the
plumbing system of Kilauea Volcano. Lava drained from Mauna
Ulu and an eruption began at Hiiaka and Pauahi craters. Lava
returned to Mauna Ulu two days later but activity was sluggish.
Late in 1973 and continuing into 1974, the intensity of activity
increased. The lava lake overflowed and lava fountains reached
heights of 250 feet.
The Mauna Ulu eruption ended
on July 19, 1974. Lava drained from the vent and the summit
of Kilauea deflated. A short time later an eruption began at
Keanakakoi Crater.
 Continuing
on Chain of Craters Road just down from the short side road
is a pulloff in 1969 lava flows. These lava flows are some of
youngest of the Mauna Ulu eruption. This is a great place to
explore. Pyroclastics from the Mauna Ulu eruption can be found
down in the cracks and on some surfaces.
Pele's tears (which can be
found in the area) are droplets of lava that solidified while
flying through the air. They are black and commonly shaped like
tear drops. Like obsidian, Pele's tears are glassy. However,
obsidian is made of rhyolite, not basalt. (The only obsidian
on the island of Hawaii is at Puu Waawaa).
Pele's hair (another local
item) is a natural spun glass formed by blowing-out during quiet
fountaining of fluid lava, cascading lava falls, or turbulent
flows.
Enjoy looking at the rocks
but remember that it is a federal offense to take anything from
a national park. Not to mention Pele never likes it when visitors
take her "children" from her home (rocks). Many people
have shipped the rocks back after being cursed by Pele for their
thefts.
The steam plume generated by
the lava entering the ocean is often visible from the pullout
at the hairpin turn. This view provides rangers and Volcanologists
with an early indication of where and what the eruption is doing.
If the plume is absent, it may indicate that there is a pause
in the eruption.
Let's now continue back on
the main road to the next area...
|
