The red dots denote significant earthquakes that have happened less than 70km below the surface

The only part of Italy without significant seismic risk is the island of Sardinia

Once again, Italy has been shaken by deadly earthquakes. Dozens of guests and staff at the Hotel Rigopiano in the Abruzzo region are missing after multiple quakes triggered a massive avalanche. The luxury hotel, in the shadow of the Gran Sasso mountain, was engulfed by snow and rubble. As the rescue and recovery continues, questions have been raised about the dangers in one of the most seismically active regions of Europe.

How many earthquakes have there been in Italy recently?

Dozens, but most of them have been of fairly modest magnitude. There have been three of greater than 6.0 magnitude on the moment magnitude scale (a more sophisticated version of the Richter scale). The events were on 24 August (6.2), 26 October (6.1) and 30 October (6.6). They have all happened in a relatively small area of central Italy, about halfway between Rome and the Adriatic port of Ancona. 

These most recent earthquakes have occurred in the Apennines, the mountain range that forms the central spine of the country. They are being pulled very slowly apart, but the earth’s crust in this region is riven with geological faults. Typically, the stresses gradually build and then release catastrophically.

Why is Italy so susceptible to earthquakes?

“Italy is one of the countries in the Mediterranean with the highest seismic risk,” says the Italian Civil Protection Department. The reason: the country lies where the African and Eurasian tectonic plates converge. They are moving together at a rate of 4-10mm a year.

“The highest seismicity is concentrated in the central-southern part of the peninsula, along the Apennine ridge, in Calabria and Sicily and in some northern areas, like Friuli, part of Veneto and western Liguria,” says Protezione Civile.

The US Geological Survey adds: “The region's tectonic activity cannot be simply explained by the collision of the Eurasia and Africa plates. It has been suggested that deeper lithospheric processes are controlling some of the deformation observed at the surface.

“The eastern Alps are particularly seismically active, with many shallow earthquakes occurring on north-dipping thrust faults, such as the M6.5 Friuli earthquake in northeast Italy on 6 May 1976 that killed approximately 1,000 people.”

The deadliest documented earthquake in Europe was on 28 December 1908, when a 7.0 magnitude earthquake in the Messina Strait between Sicily and mainland Italy killed 72,000 people. 

The only part of Italy with no significant seismic events is the island of Sardinia.

Where else in Europe is at risk?

The main issues are in the south-east, in areas on the Mediterranean Sea. The US Geological Survey issues a formidable series of reports on seismicity. Europe is covered by the Mediterranean report. It says: “The highest rates of seismicity in the Mediterranean region are found along the Hellenic subduction zone of southern Greece and the North Anatolian Fault Zone of northwestern Turkey.”

Danger areas include the area around Crete, where the Africa Plate is subducting at a rate of 40mm per year beneath the Aegean Sea. 

“Historical sources and archeological studies suggest that earthquakes occurring near Crete in 365 AD and 1303 AD may have been much larger than any Hellenic Arc earthquake of the 20th century,” says the US Geological Survey.

Further east in Anatolian (Asian) Turkey, there were 11 earthquakes of magnitude 6.7 or greater in the six decades between 1939 and 1999. They occur along the line of the North Anatolian Fault, which runs just south of Istanbul.

“The most recent and farthest west of these earthquakes was the 17 August 1999, M7.6 Izmit earthquake, which killed approximately 17,000 people,” say the American geologists.

What should I do in the event of an earthquake?

If you are indoors, traditionally the advice has been to find shelter under a beam or in a doorway. But the US Department for Homeland Security disagrees. It says: “Do not get in a doorway as this does not provide protection from falling or flying objects, and you may not be able to remain standing.”

Seven recommendations which could save your life:

1 Stay where you are until the shaking stops.

2 Drop down onto your hands and knees so the earthquake doesn’t knock you down.

3 Cover your head and neck with your arms to protect yourself from falling debris.

4 If you are in danger from falling objects, and you can move safely, crawl for additional cover under a sturdy desk or table.

5 If there is low furniture or an interior wall or corner nearby, and the path is clear, these may also provide some additional cover.

6 Stay away from glass, windows, outside doors and walls, and anything that could fall, such as light fixtures or furniture.

7 Hold on to any sturdy covering so you can move with it until the shaking stops. 

Shouldn’t I just run outside?

No. “Trying to run in an earthquake is dangerous, as the ground is moving and you can easily fall or be injured by debris or glass,” says the Department for Homeland Security. “Running outside is especially dangerous, as glass, bricks, or other building components may be falling. You are much safer to stay inside and get under a table.”

What if I’m outside when an earthquake strikes?

Move away from buildings, trees, lamp posts and power lines — anything that could harm you if it falls (including vases, windows, tiles, etc on buildings). Be aware that landslides can follow earthquakes, and that ruptured pipes can leak gas or water. The Italian authorities also warn: “Limit the use of the car to avoid obstructing the passage of emergency vehicles.”

If you are in a car, stop (but not near building, trees or overhead cables) and stay in the vehicle.

Comments