Vanuatu : " Islands of coral and ashes "
Tanna | Ambae | Karua | Ambrym | Lopevi | Gaua | Epi
of Vanuatu are located along a zone of convergence (subduction)
of the Australian and Pacific Plates. They are part of the Pacific's
"Ring of Fire", which accounts for 70% of the world's
volcanic activity. The viscosity of the magma that underlies them
gives them explosive characteristics. When a quantity of water is
also present, this results in highly spectacular "hydro-magmatic"
eruptions. In 1452, the cataclysmic explosion of Kuwae (between
the islands of Epi and Tongoa) hurled more than 25 cubic kilometres
of pulverized rock into the atmosphere.
Although it is now possible to predict the likelihood of an eruption,
it is very difficult to pinpoint the exact timing of the event.
Some of Vanuatu's volcanoes are in a state of permanent eruption
(islands of Tanna and Ambrym), others, which have been dormant for
a few decades, are now showing signs of renewed activity through
gas emissions in their crater lakes (islands of Ambae and Gaua).
Lopevi, the only Vanuatu volcano lacking a caldera, appears to follow
a 15 to 20-year cycle of dormancy and activity. Submarine volcanoes,
which will eventually give birth to islands, are evidenced on the
surface of the ocean by a discoloration of the water. They may emerge
for a time, subside, then reappear to form a new island.