The
island of Nissiros is a stratovolcano at the eastern end of the Hellenic
island arc. This arc of volcanoes is related to the northward seduction of
the African plate beneath the Aegean micro plate. Santorini, a
better-known volcano, is west of Nisyros the base of the island is made of
hyaloclastite, lava flows, and breccias, mostly of andesine composition.
Pyroclastic deposits and volcanic domes of dacite composition cap these
rocks. The pyroclastic deposits are related to two explosive phases of the
volcano. The volume of magma erupted was great enough to cause the summit
of the volcano to collapse, making a caldera. The two explosive phases
were probably several thousand years apart and occurred roughly 25,000
years ago. After the caldera formed, eruptions produced the lava domes.
It is suspected that the volcano erupted in 1422. In 1871, earthquakes,
detonations, and red and yellow flames accompanied an eruption. Ash and
lapilli were erupted and covered the floor of Rammos, destroying the fruit
gardens there. During a three-day-long eruption in 1873, a 20-25 foot (6-7
m) diameter crater formed and ash and blackish mud was ejected. The bottom
of Lakki and Ramos was transformed into a lake by hot saline water that
overflowed the crater. The most recent eruption was in 1888. This strong
eruption threw out a cylindrical pipe of volcanic material at least 80
feet (25 m) in diameter. Mud, lapilli, and steam were also ejected. In
1956, fumaroles were observed along the west and south sides of Rammos.
In
antiquity Nissiros it was known as Porphyris. Mythology holds that once it
was united with Kos and
that when Poseidon was chasing the giant Polyvotis, he
split the two islands asunder.
Perfectly white houses, dense greenery and the colours of the volcanic
soil palette, and a capital city built at the foot of the hill and which
used to be fortified in the Middle Ages.
