The region surrounding Naples is well known for two two of its active volcanoes, Vesuvius,
and the Campi Flegrei supervolcano. However, they are not the only dangerous volcanoes present in
the region. Just off the Italian mainland is a third volcano, Ischia. This island is
completely volcanic in origin, and has erupted more than a dozen times since it was settled.
This video will discuss this active volcano, and mention what its future hazards are.
The island of Ischia can be found along the west coast of a portion of central Italy. Specifically,
it is 18 kilometers southwest of Pozzuoli, and 30 kilometers west-southwest of Naples.
The Ischia volcano is the oldest of the 3 volcanoes in the region, as it began
forming 150,000 years ago. So, why isn't it as tall as Mount Vesuvius? The reason
for this is that the majority of the original island was destroyed when it
collapsed into the Mediterranean in a massive eruption tens of thousands of years ago.
What you see today merely represents activity AFTER this large collapse.
These early eruptions from Ischia were highly explosive in nature, due to the highly siliceous
trachyte lavas they erupted. As a result, these eruptions built a number of relatively steep
peaks, such as Monte di Vezzi which formed 130,000 years ago. Over tens of thousands of years,
several other lava domes built a number of additional peaks in southeastern Ischia.
The first major eruption from this volcano occurred on the southwestern portion of the
island, about 100,000 years ago. Over the course of this plinian eruption,
about 90 meters of lava and ash was deposited at a vent known as L’Elefante.
Small volcanic eruptions continued throughout the island until about 73,000 years ago when
the volcano became dormant. Over the next 15,000 years, pressure built up underneath the island.
Then, 56,000 years ago, this pressure was released via a catastrophic eruption at the center of the
island. From this eruption emerged a series of pyroclastic flows which raced in every direction
across the Mediterranean sea, and likely traveled for up to 30 kilometers before they stopped.
Eventually, the volume of lava and ash ejected was so large that it caused the center of the
island to collapse into the Mediterranean Sea, thus forming a 7.5 kilometer wide caldera.
All that remained of the once large island were sections of its edge.
However, the center of Ischia did not remain as part of the Mediterranean sea for long.
In the underlying magma chamber, lava soon began filling the area filled by the caldera collapse.
This pushed a large section of the island upwards in what is termed a resurgent dome.
By 33,000 years ago, the center of the island had been uplifted by 600 meters and was once again
above sea level. However, the uplift across the caldera was not even. The northern section of the
island was uplifted far more than the southern section. As a result, much of the southern
section of the resurgent dome slid off into the Mediterranean in a series of large landslides.
This uplift in the region created a series of weak points in the crust known as faults.
In the southwestern section of the island, this allowed magma to reach upwards and erupt onto
the surface around 28,000 years ago. Over the next 10,000 years, frequent eruptions built
a number of features in the region, which included a 750 meter wide explosion crater.
Eventually, eruptions shifted to a different section of the island. In 3880 BC,
a long duration eruption via a large lava dome added a square kilometers of land to the island.
Since this eruption, activity has ONLY taken place on the eastern two fifths of Ischia.
One of these eruptions in 370 BC formed a large explosion crater which is now largely underwater.
This crater is now the site of the main port on the island. (pause 2 seconds)
Another eruption in 302 AD created a large eruption created 4 distinct lava domes. The
most recent eruption from Ischia occurred in 1302, when a spatter cone known as Arso created
a lava flow which traveled to the northeast. Although there is no evidence in the short term of
an imminent volcanic eruption, Ischia will erupt again. This volcano is by no means overdue for
an eruption, but on average it has erupted once every 250 years. When the next eruption occurs,
it will either create a new tuff ring, lava dome, or lava flow. Regardless,
the next eruption WILL be quite explosive, and due to the population density of the island, no part
of it will be safe during an active eruption. I hope that you enjoyed this video. If
you would like to request a specific topic, please leave a comment below!