New Zealand contains more than a dozen active volcanoes,
including the world's most recent supervolcanic eruption from Lake Taupo.
Of the 21 monitored volcanoes in the country, none are as active as the White Island volcano.
This volcano has produced 40 distinct eruptions since 1826, the most recent of which occurred
in 2019. This video will discuss this active volcano, and mention what its future hazards are.
In New Zealand, volcanic activity is currently confined to the north island, and a chain of
volcanoes to the north of the main island. The White island volcano can be found north of the
bay of plenty in the Pacific Ocean. Specifically, it is 51 kilometers NNE of the town of Whakatane.
This volcano is part of a chain of volcanic activity known as the Taupo volcanic zone.
It exists due to the subduction of the Pacific plate underneath the Australian plate.
The subducted crust from this collision then melts and migrates upwards until
it erupts on the surface, creating a volcano. The White island volcano began forming 150,000
years ago, when it started erupting from the bottom of the pacific ocean. Over many thousands
of years, this submarine volcano continued to erupt and slowly became taller. Eventually,
this stratovolcano reached the surface. The main eruptive cone of the volcano at this time was the
Ngatoro cone on the northwest portion of the island. Eventually, eruptive activity shifted
to the central cone. After numerous eruptions of andesite and dacite lava, the White Island
volcano stood at 550 meters above sea level. Then, 2600 years ago, the volcano suffered a
catastrophic collapse. This collapse caused much of the central cone to slide off to the southeast
into the Pacific Ocean. This created the modern ampitheater shape of the volcano's south side
and generated a 7 meter high tsunami which hit the bay of plenty. This landslide was relatively
similar to the 2018 collapse and tsunami at the Anak Krakatoa volcano in Indonesia.
In 1769, James Cook spotted the island and witnessed rising steam and gas from the volcano.
However, official records of this volcano's eruptions began only in 1826.
During the 19th century, 7 volcanic eruptions were recorded at White Island. In 1913,
a mining camp was built on the island to mine sulfur. However, this activity was
abandoned when part of the crater rim collapsed. The largest and longest eruption recorded at White
Island occurred from 1976 to 1982. This eruption was rated on the volcanic explosivity index as
a 3, and caused lava bombs to be ejected from the volcano's vents. In 2012, another eruption
occurred, which formed a spiny looking lava dome. Then, on November 18th, 2019, the volcano's alert
level was raised from 1 to 2. This is the highest alert level possible which does not signal
an active eruption. This alert level remained until December 9th, when the volcano erupted.
This eruption did not produce any lava, as it was considered a phreatic eruption. Phreatic
eruptions occur when groundwater is heated by magma. Eventually, the water flashes to steam,
and generates a large explosion. This phreatic eruption generated a deadly pyroclastic flow, a
tall column of ash, and caused several fatalities as tourists were on the island when it happened.
However, no one should have been anywhere near the island during its raised alert status.
These alert levels exist for a reason. It is true that phreatic eruptions are almost impossible
to predict. However, they become far more likely during increased periods of activity at a volcano.
So, what hazards does the white island volcano pose in the future?
Despite what certain tabloids say, this volcano is not in any danger of generating a new
tsunami. The most significant hazard it poses in the event of a new eruption is from its ash cloud.
Ash clouds can damage aircraft, and as a result an airspace exclusion zone needs to
be declared during an eruption. The eruption in 2019 was a rather average sized eruption,
with a rating on the volcanic explosivity index of 2. Future eruptions will be about the same size,
and could create pyroclastic flows, violent explosion craters,
and erupt lava onto the surface. I hope that you enjoyed this video.
If you would like to request a specific topic, please leave a comment below!