MAUNA LOA VOLCANIC ERUPTIONS - GEOGRAPHY
News: Mauna
Loa volcano in Hawaii erupts: What is the science behind volcanic eruptions?
What's in the news?
● Mauna
Loa, the world’s largest active volcano, erupted after 38 years on Sunday
(November 27), spewing ash and debris, and covering the night sky of Hawaii’s
Big Island in an incandescent red hue.
Volcano:
● It
is a rupture in the crust of a planetary-mass object (like Earth), that causes hot lava, volcanic ash, and gases to
escape from a magma chamber below the surface.
● On
Earth, volcanoes are generally found where tectonic plates (like Eurasian,
Pacific, Somali, etc) diverge or converge. Examples- volcanoes occurring in mid-oceanic ridge and Ring of Fire.
● Eruption
of volcanoes can be hazardous for humans and other lives living in its vicinity
and volcanic ash may be a threat to aircrafts. Volcanoes can also cause
● Large
volcanic eruptions inject water vapor
(H2O), Carbon Dioxide (CO2), Sulphur Dioxide (SO2), ash, etc into the
stratosphere to heights of 16-32 km.
Magma:
● Magma
is lighter than solid rock and hence it rises, collecting in magma chambers.
● Chambers
which have the potential to cause volcanic eruptions are found at a relatively
shallow depth, between six to ten km under the surface.
● As
magma builds up in these chambers, it forces its way up through cracks and
fissures in Earth’s crust. This is what we call a volcanic eruption.
● The
magma that surfaces on the Earth’s crust is referred to as lava.
Types of volcanoes based on frequency of eruption:
1. Active Volcano:
● Active
volcanoes are volcanoes that are either
erupting or on the verge of eruption.
● There
are around 500 active volcanoes on Earth, excluding those submerged beneath the
oceans.
● Every
year, approximately 50 to 70 active volcanoes erupt, most of them being around
the pacific “ring of fire”.
● Mount Etna (Italy),
Hawaiian Islands (Pacific Ocean), Mauna Loa (Pacific Ocean), Mount Vesuvius
(Italy), and Barren Island (India) are some examples
of Active Volcanoes around the world.
2. Dormant Volcano:
● A
dormant volcano is one that is not
erupting at the present but has erupted in the past and is expected to erupt
again.
● The
distinction between active and dormant volcanoes can be hazy.
● Some
volcanoes can last thousands of years without erupting, thus they are
theoretically predicted to erupt in the future, but it could take many lives.
● Another
of the Big Island's five volcanoes,
Mauna Kea, last erupted 3,500 years ago, but it is predicted to erupt again,
but no date has been set.
● People
living in the neighborhood of dormant volcanoes are frequently complacent and
unprepared when an eruption occurs.
● This
was the case in 1980 with Mt. St.
Helens.
3. Extinct Volcano:
● Extinct
volcanoes are considered to be dormant
and unlikely to erupt again.
● Example:
Kohala, the Big Island of Hawaii's
oldest volcano, hasn't erupted in 60,000 years and isn't expected to erupt
again.
● However,
because many Hawaiian volcanoes are in the process of rejuvenation, this
classification isn't completely accurate.
● Aconcagua of the Andes
is a typical example of an extinct volcano.
Some famous volcanoes in the world: