Recently, Mauna Loa. the world’s largest active volcano, erupted after 38 years, spewing ash and debris, and covering the night sky of Hawaii’s Big Island in an incandescent red hue.
GS I: Geography, Facts for Prelims
Dimensions of the Article:
- Where is Mauna Loa?
- Why do volcanoes erupt?
- Some famous volcanoes
Where is Mauna Loa?
- Mauna Loa is one of five volcanoes that together make up the Big Island of Hawaii, which is the southernmost island in the Hawaiian archipelago.
- It’s not the tallest (that title goes to Mauna Kea) but it’s the largest and makes up about half of the island’s land mass.
- It sits immediately north of Kilauea volcano, which is currently erupting from its summit crater.
- Kilauea is well-known for a 2018 eruption that destroyed 700 homes and sent rivers of lava spreading across farms and into the ocean. Mauna Loa last erupted 38 years ago.
- In written history, dating to 1843, it’s erupted 33 times. The Big Island is mostly rural and is home to cattle ranches, coffee farms and beach resorts.
- It’s about 200 miles (320 kilometers) south of Hawaii’s most populous island, Oahu, where the state capital Honolulu and beach resort Waikiki are both located.
Why do volcanoes erupt?
- The deeper one goes under the surface of the Earth towards its core, the hotter it gets.
- The geothermal gradient, the amount that the Earth’s temperature increases with depth, indicates heat ﬂowing from the Earth’s warm interior to its surface.
- At a certain depth, the heat is such that it melts rocks and creates what geologists call ‘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.
Some famous volcanoes
- Any volcano that has erupted within the Holocene period (in the last 11,650 years) is considered to be “active” by scientists.
- “Dormant” volcanoes are those active volcanoes which are not in the process of erupting currently, but have the potential to do so in the future.
- Mauna Loa was a dormant volcano for the last 38 years.
- “Extinct” volcanoes are ones which scientists predict will never face any further volcanic activity.
- Ben Nevis, the tallest mountain in the UK, is an extinct volcano.
Here are some famous volcanoes in the world.
- One of the most catastrophic volcanic eruptions ever occurred in Krakatoa in 1883 (VEI 6). The volcano released huge plumes of steam and ash.
- The explosions were so brutal, they were heard 3,100km away in Perth, Western Australia. According to the Dutch colonial authorities, Krakatoa’s eruption and the consequent tsunamis caused 36,417 deaths, though modern estimates peg the number to be much higher.
Mount Vesuvius, Italy
- In 79 CE, Mount Vesuvius erupted (VEI 5), in one of the deadliest eruptions in European history, killing as many as 16,000 and destroying the town of Pompeii.
- According to scientists, the explosion released 100,000 times the thermal energy that was released with the atomic bombings at Hiroshima and Nagasaki.
- It is said to have instantly boiled the blood of all those who were too close to it.
Mount Fuji, Japan
- A defining image of Japan, Mount Fuji towers over the countryside with its snow-capped peaks and barren surface.
- It last erupted in 1707-1708 (VEI 5) and had a devastating effect on the local population.
- The tephra release led to significant agricultural decline, leading to widespread starvation in the Edo (now Tokyo) area.
- Although this eruption itself did not directly kill a lot of people, its subsequent impact proved deadly.
- Sometimes referred to as E15, it is one of the many volcanic features of Iceland.
- In 2010, a relatively small eruption (VEI 4) managed to bring air traffic in Europe to a complete standstill.
- 20 countries closed their airspace, impacting approximately 10 million travellers.
- Adjacent to the Mauna Loa, this is one of the most active volcanoes on the planet. It has been erupting intermittently since recorded history, with its eruption lasting from 1983 to 2018 being the longest continuous eruption ever recorded.
- It is a major tourist attraction, with the earliest hotel built at the edge of the volcano in the 1840s.
Mount St Helens, USA
- Located in Washington State, Mount St. Helens was a major eruption that occurred on May 18, 1980 (VEI 5), and it remains the deadliest and most economically destructive volcanic event in U.S. history.
- It started after an earthquake hit the region, killing 57 and causing property damage over $1 billion.
- It remains an active volcano and one that is considered to be amongst the riskiest by scientists.
-Source: Indian Express