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It is a law of nature that when something begins, it ends one day,
sooner or later. Just like everything else, the Hawaiian volcanoes don’t
make an exception. Their existence passed through three development
stages – birth, maturity and old age.
The Birth of Hawaii’s Volcanoes
The Hawaiian volcanoes’ birthplace is known to be 2.5 to 3 miles (4
to 5 km) under the ocean’s surface. The outpouring of the lava created
underwater mounds that were coming closer and closer to the surface
as years went by. This process of outpouring was slow and lasted for
thousands of years.
When the volcano is within at about 330 feet (100 m) of the surface,
it produces steam explosions that throw ash in the air. The volcano
continues its eruption activities and it grows as a mountain above the
surface. It is known that the oldest of Hawaii’s volcanoes, Kohala Volcano,
has broken the surface of the ocean exactly in this manner million of
years ago.
Scientists have found that about 15.5 miles (25 km) south of the Big
Island of Hawaii, another volcano has started to form. Its seamount
is slowly coming closer to the surface. However, the newly forming Hawaiian
volcano it is not expected to break the ocean’s surface within the next
few thousands of years.
Although it is difficult to determine the length of the Hawaiian volcanoes
youth stages, there are specific signs that can tell when they are about
to end. The tops of most Hawaiian volcanoes collapse and form large
craters, known as calderas.
Maturity – the Caldera’s Stage
The volcanoes’ maturity, also known as the caldera stage, is characterized
by many volcanic activities, such as repeated collapses and refilling
of the volcanoes’ calderas. The length of this age lasts for thousands
of years. Mauna Loa and Kilauea on the Big Island are now in this stage.
The process of caldera forming is not known in detail, and there are
not many explanations about why the activity of this stage comes gradually
to its end. However, it is assumed that it is related to the cooling
of the magma, which leads to a decrease of volcanic activity. Toward
the end of this stage, the caldera gradually fills, and at the end it
completely vanishes.
Volcanoes Old Age
The volcano is in its old stage when the caldera is filled and when
the top of the shield is covered with a sleepy cod. As the age of the
volcano increases, the lava’s chemical components start to change and
contain different substances, rich in sodium and potassium.
Mauna Kea and Haleakala have gone through this stage and the different
types of rocks appearing along the old ones attest that. Usually, old-age
eruptions form steep cinder cones and are more explosive than eruptions
in the earlier stages. For other volcanoes, such as Kahala, the eruption
activities stop for thousands of years and then start again and create
completely different types of rocks. |
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