In
1998, the activity of Etna began to become more varied than in 1997,
and, most of all, it significantly gained in intensity. Following
a somewhat erratic period in January-February (accompanied in mid-January
by an intense seismic swarm probably caused by magma intrusion below
the western flank), and an isolated paroxysm at the Northeast Crater
in late March, the activity picked up in the spring and early summer,
with spectacular lava fountains and explosions in the Voragine and
the Bocca Nuova. This culminated, on 22 July, with a powerful paroxysm
at the Voragine, which produced an enormous, mushroom-shaped eruption
column 10 km high and heavy tephra falls around the volcano. Shortly
thereafter, the Southeast Crater, which for nearly two years had
been the site of a marvellously faithful persistent Strombolian-effusive
activity, fell in complete silence. In mid-September, when the activity
at the neighboring Voragine and Bocca Nuova began to wane, the Southeast
Crater reawoke violently, and for a few days it seemed as though
it had resumed the regular persistent activity of the previous period.
However, it soon became clear that this was not the case. Instead,
the activity now consisted of brief, violent, and exceptionally
spectacular episodes of lava fountaining and lava flow emission.
These paroxysms at the Southeast Crater continued into 1999, heralding
an even more exciting period of summit activity... |