Tanna | Ambae | Karua | Ambrym | Lopevi | Gaua
Yasur, the most accessible active volcano
in the world
Coral dating and GPS
measurements | Devastating
acid rains | Formidable
volcanic bombs | Monitoring
Yasur's activity | Seismic
activity, torrential rains, landslides | Volcanic
hazard for the population
Tanna Island belongs to the central portion of
the New Hebrides Arc, a 3 to 6 million year-old complex extending
from the Banks Islands in the north to Hunter Island in the south.
There, the subduction
rate averages 118 mm per year. Volcanic activity began about 3 million
years ago with the formation of the "Green
Hill" series. Today, this activity is limited to the Yenkahe
volcanic complex, with the Yasur
occupying the western portion (latitude 19.52°S, longitude 169.43E).
Yasur's current activity, documented
now for at least 200 years, is of the Strombolian and Vulcanian
type. Over the last ten thousand years or so, lava and pyroclastic
flows have occurred, building up the old volcanic cone of Ombus.
The summit of Yasur reaches 365 m altitude, and its activity varies
in intensity. Five alert
levels have been defined (0 to 4).