The Sumatra Earthquake/Tsumami of December 26, 2004, was the result of the collision of the Indian and Asian Tectonic Plates, that forced the ocean floor upwards by 30 metres (100 ft/10 story bldg).

This Geological Episode has aroused a great interest and concern world wide about Local Past and Potential Geological Disasters, and no place moreso than Italy.

Italy sits on the has a long history of geologic catastrophes, both Earthquakes and Volcanoes.

Italy has had more than 400 destructive earthquakes documented during the last 2,000 years, almost half of all those ever occurring in Europe, and therefore acquired a reputation as being one of the most earthquake-prone countries in the world.

Italy also has Four (4) Active Volcanoes: Vesuvius, Mt Etna, Stromboli, and Vulcano, the ONLY Active Volcanoes on the entire European Continent

VOLCANOS:

Vesuvius, the only active volcano on the European continent. The name, Vesuvius or Vesbius means 'unextinguished'. People still choose to settle near Vesuvius as well as around Mt. Etna in Sicily because the volcanic ash provides rich soil suitable for producing excellent wine grapes. The wine produced from the grapes around Vesuvius today is called 'Lacrima Christi'. People feel secure because tranquil times can last up to 2000 years.( About due??)

However, as long as the volcano is active, they are living atop a live bomb. Today there are over 2 million people living in the vicinity of Mount Vesuvius.

Vesuvius has erupted repeatedly in recorded history, most famously in 79, and more than 50 times since, subsequently and significantly in 472, 512, in 1631, six times in the 18th century, eight times in the 19th century, (notably in 1872), and in 1906, 1929, and 1944.

It is today regarded as one of the most dangerous volcanoes in the world.

Incredibly, Vesuvius may not even pose the biggest threat to the region. For in reality, the landscape surrounding Naples and its bay is pockmarked by scores of volcanoes in an area known as the Phlegraean Fields.

Known during the Roman era as the gateway to the underworld and believed to be the inspiration for Dante's "Inferno," the Phlegraean Fields is composed of 40 small volcanoes clustered in the midst of a massive, eight-mile-wide caldera formed by the eruption of a massive volcano 34,000 years ago.

Mount Etna (or Aetna, and known locally as Mongibello) is an active volcano on the east coast of Sicily (Italian Sicilia), close to Messina and Catania. It is the largest volcano in Europe, standing about 3,320 m (10,900 ft) high with a basal circumference of 140 km, making it the highest mountain in Italy south of the Alps.

Etna covers an area of 460 square miles (1190 km²). It is by far the largest of the four  active volcanos in Italy, being nearly three times the height of the next largest, Mount Vesuvius. It is one of the most active volcanoes in the world and is in an almost constant state of eruption. Although it can occasionally be very destructive, it is not generally regarded as being particularly dangerous.

Etna is known to have erupted over sixty times in recorded history. Only vague records of Etna's ancient eruptions survive. The earliest recorded eruption was that of about 475 BC.

In 1169 and 1669, immense lava flows descended the flanks of the mountain, reaching the sea and destroying Catania on both occasions. In 1928, the town of Mascali was destroyed by lava. Other major 20th century eruptions occurred in 1949, 1971, 1991, and 2000. In 2001-2002, the biggest series of eruptions for many years threw up a huge column of ash that could easily be seen from space and fell as far away as Libya.

In Italy, there are Four Active non-submarine Italian volcanoes.
Aside from the aforementioned Mount Vesuvius, and Mount Etna, there are
Stromboli, one of the Aeolian Islands (continuous activity), and
Vulcano, another of the Aeolian Islands (last erupted 1888-1890).

Italy also has a number of Dormant and Submarine volcanoes:
Pantelleria, off the coast of Tunisia, probably last erupted around 1000 BC.
There was a submarine eruption a few kilometres north-east of the island in 1891.
The short-lived Isola Ferdinandea erupted a few kilometres north-west of Pantelleria in 1831 and rose to a maximum height of 63 metres, but was quickly eroded back down to sea level by 1835 and the top is now 25 metres below the surface.
Ischia, an island 20 kilometres west of Naples, last erupted in 1302.
Lipari, an island a couple of kilometres from Vulcano, which last erupted in 729. Monte Nuovo in the Campi Flegrei caldera just north of Naples, erupted in 1538. Vulcanello is a small volcano connected by an isthmus to the island of Vulcano, which erupted out of the sea in 183 BC and showed occasional activity thereafter until the 16 century.
Monte Albano near Rome, erupted in 114 BC.

EARTHQUAKES:

Italy has a long history of seismic catastrophes, with more than 400 destructive earthquakes documented during the last 2,000 years.

The convergence of the Eurasian and African plates across the Mediterranean has resulted in a wide zone of collisional tectonics and microplates. It is the relative motion along these microplate boundaries that generates most of the earthquakes observed in Italy.

Seismic activity varies considerably from region to region within the country. The regions with the highest activity are associated with three main tectonic features: the Apennine mountains along the center of the Italian peninsula, the Alps in northeast Italy, and the Calabria-Sicily region of southern Italy.

The highest seismic activity occurs along the Apennine Mountains, where one of the most severe events in Italy’s recent history occurred. This event, the 1980 Irpinia Earthquake, had a magnitude of 6.9 with estimated losses of US $10 billion (1980 dollars). The Alps region of northeastern Italy also experienced a similar size event when the Friuli Earthquake struck in 1976 causing US $2.6 billion in damage. This was the most serious earthquake to hit northern Italy since 1887.

The magnitude 7.3 Messina Earthquake of 1908 occurred in the Calabria-Sicily region, and was one of the most severe events in Italy’s recorded history destroying 98% of the buildings in some city centers.

The Calabrian region is rich with stories of cultures accommodating themselves to a violent seismic landscape. Half of the 7.0 earthquakes that occurred in Italy during the past centuries had their epicenters in the long and narrow Calabrian peninsula.

The scenario of death and destruction from earthquakes has extended from coast to coast of Calabria, as the abandonment of dozen of villages and the exodus of the survivors toward safer lands recurred each time.

The Question is Not IF,..... BUT When, Where, and How Severe will the next Earthquake be?

To give you some perspective, below is listed Earthquakes in Italy, but only in the last 500 years, and only with greater than 30,000 deaths:

1638, March-June CALABRIA

A strong seismic sequence occurred between March and June 1638, with 2 main
shocks on 27 March and 9 June  The catastrophic 27 March event struck a thickly populated area between the high Crati Valley and the Catanzaro strait area,
while the second one devastated the Ionian hillslope of the Sila massif.

1693, Jan 11- Catania, Sicily & Naples, 143,000 Perished

1783,  Nearly 1,000 earthquakes in a two-month period destroys 180 towns in Calabria and kill more than 60,000 people. Messina, 50,000 Perish

1908, Messina/Calabria, Up to 200,000 Perished
The greatest in Italian and Europe History

1915, Avezzano., 30,000 deaths

Also, within the last 30 years, among a number of Earthquakes, FIVE measured more than 6.0 on the Richter scale:

1976 A.D. - An earthquake measuring 6.1 on the Richter scale rocks Friuli in northeastern Italy, killing 976 people and leaving 70,000 others homeless.

1980 09 15 Northeastern Italy 6.0  Two earthquakes occurred within 6 hours of each other. Eleven reported killed, some injured, and caused extensive damage in the already stricken area, leaving an additional 20,000 people homeless. The earthquakes were also felt sharply throughout central Europe.

1980 11 23 Southern Italy 7.2 Over 3,000 people killed, about 1,900 missing, 7,750 injured, 250,000 homeless and extensive damage in a 25,000 square kilometer area of Campania and Basilicata.

1997 A.D. - Richter 6.0. More than 40,000 people lose their homes and 13 die in a series of earthquakes in September. Four of the victims are killed as the roof of the Basilica of St Francis in Assisi collapses. Priceless frescoes are also damaged

2002      Sicily Italy Richter 5.9 Two people died from heart attacks, twenty injured and some buildings damaged in the Palermo area. Also felt at Agrigento, Caltanissetta, Catania, Enna, Messina and Trapani.