Within the Solomon Islands is a relatively unique volcano which is most notable for the
large population of sharks that live within its active crater.
Despite the high acidity and temperature of the water, species of both hammerhead sharks
and silky sharks live and thrive on the Kavachi volcano.
Their survival is made all the more interesting by the nature of Kavachi's volcanic eruptions.
During its frequent eruptive episodes, superheated ash and lava is emitted into the crater which
causes above water to flash to steam.
All of this material travels upwards, subsequently creating a powerful explosion that ejects
water, volcanic gasses, lava fragments, and superheated ash.
These explosions occur at irregular intervals, and any animals within the submarine volcanic
crater would be wiped out when one occurs.
The mystery of how these animals stay alive likely relates to the sharks having a high
degree of favorable mutations which allowed them to survive in this extreme environment.
Also, although not proven, it is quite likely that something alerts these sharks that an
explosion is about to occur and causes them to leave the volcano temporarily.
This video will discuss the fascinating Kavachi volcano, which is sometimes colloquially referred
to as a "sharkcano".
The Kavachi volcano is located in the southwest Solomon Islands, where it is 53 kilometers
south-southwest of the city of Batuna.
It is one of the nation's 8 active volcanoes, of which it is by far the most active.
In fact, it is erupting right now and has been erupting since October 2nd of 2021.
The reason why this volcano exists is due to a tectonic plate collision which is occurring
southwest of its edifice.
There, the Australian Plate is subducting underneath the Pacific Plate.
The melted material from this collision then migrates upwards, until it erupts on the surface,
thus forming a chain of volcanoes.
Although the true age of the Kavachi volcano is unknown, its current eruptive rate suggests
that the volcano is between 5,000 and 20,000 years old.
Its edifice is 8 kilometers wide, and begins at a depth of 1100 meters or 3600 feet on
the ocean floor.
It is composed out of volumes of ash in addition to both basalt and andesite lavas.
The higher viscosity of the andesite magma is one cause of the volcano's more explosive
eruptions.
When this volcano first began erupting several thousand years ago, the water pressure at
1100 meters depth was sufficient to mitigate the potential for an explosive eruption to
occur.
Instead, large volumes of lava spilled onto the ocean floor, and over time built a volcanic
cone.
Eventually, the summit of this stratovolcano got within 100 meters of the ocean's surface.
At this meager depth, the eruptive style of the volcano changed, from largely effusive
submarine activity to a surtseyan eruption.
Surtseyan eruptions are highly explosive as the water amplifies the energy of released
magma and ash.
They are characterized by white and black plumes which produce small pyroclastic flows
and quantities of ash like seen in this video of Hunga Tonga Hunga Ha'apai erupting in December
of 2021.
This style of eruption occurs at almost any volcano that has an active vent close to or
just above the ocean surface.
While the smaller explosive eruptions leave behind only small quantities of fragmented
ash and lava, the larger eruptions are sometimes able to build small volcanic islands.
One such island was built due to an eruption in 2003, which at one point had a summit 15
meters or 49 feet above sea level.
However, since this island was mainly composed of ash it eroded away quite easily within
a few months.
The formation of peripheral islands at Kavachi has occurred 9 times since its first documented
eruption in 1939.
In other words, about 1 in 4 of its eruptions form temporary volcanic islands.
If you decide to visit this volcano, keep at least 3 kilometers away from its summit.
Additionally, aircraft could be put at risk during Kavachi's eruptions due to low lying
clouds of ash.
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