MERAPI
VOLCANO - GEOGRAPHY
News: Indonesia's Merapi volcano erupts,
covering villages in smoke and ash
What's
in the news?
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Indonesia's
Mount Merapi, one of the world's most active
volcanoes, erupted spewing out smoke and ash that blanketed villages near the
crater.
●
There were no immediate reports of
casualties.
●
The Merapi Volcano Observatory estimated
that the ash cloud reached 3,000 metres above the summit.
Key
takeaways:
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Merapi, on densely populated island of
Java, unleashed clouds of hot ash and a mix of gas and lava that travelled 7 Km
down its slope.
●
It was the biggest lava flow since
authorities raised the alert to second-highest in 2020. Residents living on
slopes were advised to stay 7 km away.
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 neighbourhood 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:
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Extinct volcanoes are considered to be dormant and unlikely to erupt again.
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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: