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Seismic Event – Central Italy: Post Event Review

2016/08/28

No Culture of Prevention

August 26, 2016

(Berkeley Seismo Blog) As of this writing, the death toll of Wednesday’s earthquake in Central Italy has risen to 280. However, rescue workers expect to find more bodies in the rubble in the three mountain communities most affected by the shaking of the magnitude 6.2 quake: Armatrice, Accumoli and Arquata del Tronto. Of particular worry is the situation in Armatrice, where a hotel has completely collapsed. Many tourists had spent the week there to attend the town’s annual Pasta Festival. The celebrated specialty dish, Spaghetti all’armatriciana“ is well known all over Italy.

Rescue and recovery teams sort through ruble in the town of Armatrice.

Rescue and recovery teams sort through ruble in the town of Armatrice. Image: Berkeley Seismo Blog

While rescue and recovery work is still continuing in the epicentral region, experts have begun to ask why relatively weak earthquakes always seem to generate enormous amounts of death and destruction in Italy. Compare, for instance, the Napa earthquake that occurred in Northern California almost exactly two years ago with Wednesday’s temblor in the Italian Appenine mountains. With a magnitude of 6.0 the Napa quake was just a tad smaller than the magnitude 6.2 quake in Italy. But only one person was killed in California’s wine country and the damage to buildings and structures was far less than the severe destruction in Italy. Elsewhere in the industrialized world even much stronger earthquakes with magnitudes of 7.5 or more do not generate as much damage as it seems to be the norm for smaller quakes in Italy.

Take the L’Aquilla event from 2009 with a magnitude of 6.3, only 25 miles from Wednesday’s temblor: 300 people died and more than 10,000 buildings were destroyed. In 2002 more than 30 people, among them 27 pupils, died in a magnitude 5.9 quake south of the current epicenter. Other devastating Italian quakes also do not belong into the class of strong or severe earthquakes: One near Assisi in 1997 with a magnitude of 6.4 caused 11 fatalities, in a magnitude 6.4 quake south of Naples in 1997 more than 2700 people died and one thousand were killed in the Friuli quake of 1976 (M=6.5).

One reason for the enormous destruction caused by relatively small quakes in Italy can be traced to the age of many buildings, particularly in small, rural towns and villages. Many structures there date back centuries or even to the Middle Ages. When they were built, nobody cared or had a clue about earthquake resistant construction methods. However, earthquake engineers have also encountered modern buildings which did not comply with those aspects in the Italian building code, which relate to earthquake safety and resilience. The 27 pupils mentioned earlier died in a modern school building in the town of San Giuliano di Puglia. It turned out that during its construction the earthquake safety measures required by law were bypassed or ignored.


One historic building remains in the city of Armatrice after Wednesday's quake.
Built by modern standards: The red building in this picture is the only structure in the historic center of Armatrice left undamaged by Wednesday’s quake. Photos: AP

Another reason is that – in contrast to other industrialized countries located in seismic zones – Italy does not have seem to have a culture of preparing for natural disasters. This sentiment was echoed after Wednesday’s quake by Francesco Peduto, the president of Italy’s National Council of Geologists. He said in a newspaper interview, that Italy was “lacking a culture of disaster prevention”. He added that 40 percent of the 60 million Italians live in zones with a high natural hazard, mostly due to seismic activity but also in volcanic zones, like those around Vesuvius near Naples and Etna in Sicily. Even in areas with high seismic risk, there is little education of the general public on how to behave during earthquakes. While in Japanese and California schools kids are regularly taught to “Drop, Cover and Hold on” when they feel seismic shaking, very few Italian schools have any disaster drills. Peduto estimated that between 20 and 50 percent of all deaths in earthquakes could be avoided, if people knew how to react properly when shaking starts.

Another critic is Massimo Cocco, one of the research directors of the Italian National Institute for Geophysics and Volcanology (INGV). He estimates that almost 70 percent of Italy’s buldings are built with little or no earthquake resistance. The Italian government, he claims, does not even have a “Earthquake Safe” plan for schools and hospitals. Peduto concurs and demands nationwide legislation to enforce earthquake retrofitting. Not only would such a measure reduce the loss of life, it would also save money in the long run. The national Association of Builders, an industry group, estimates that since 1968 Italy has spent about 200 billion Dollars in reconstruction and recovery efforts after earthquakes. Applying well tested retrofitting and building techniques to increase earthquake resistance would have cost a fraction of that amount, Peduto notes. (hra126)


MWP6.2 Central Italy

Recent Earthquakes Near Accumoli, Latium, Italy

More information at:

Italian National Seismic Network Roma, Italy
EMSC Special report

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Another Tragedy in the Heart of Italy

(Berkeley Seismo Blog)The strong magnitude 6.2 earthquake that shook Central Italy around 3:30 this morning (local time) must have revived horrible memories for many people in the Rieti and Abbruzo regions about 100 miles north-northeast of Rome. Seven years ago, a temblor of similar size shook the same area and left the medieval town of L’Aquila in ruins. More than 300 people died in that quake, which has become one of the most infamous temblors in recent Italian history. First reports about today’s quake in Italian media put the death toll at about 120. The reports speak of strong shaking and widespread damage.


Earthquakes plotted in central section of Apennine mountains.
Earthquakes in the central section of the Apennine mountains in Italy. Wednesday’s quake (yellow star) in the center is almost masked by aftershocks, less than 24 hours after its occurrence. The two blue stars north and south indicate the epicenters of previous quakes with similar magnitudes. Source: EMSC, Strassbourg.

Earthquakes in central Italy are a direct consequence of the complex collision of two tectonic plates. Although geographically a European country, Italy is actually a nail shaped protrusion of the African plate which rams into Europe, creating the Alps far north of this morning’s epicenter. This collision has also created the Apennine Mountains. They run along the shaft of the “boot” which Italy resembles when viewed on a map. The Apennines are dominated by a series of north-south trending earthquake faults, which run parallel to the crest of the mountain range through most of central Italy. The epicenters of both the 2009 earthquake and today’s quake lie less than 25 miles apart on those fault lines. Today’s quake occurred near the town of Amatrice to the north-northwest of L’Aquila.


Map of seismic rick in the Italian Apennines.
Map of the seismic risk in the Italian Apennines: areas in green and blue are considered very low risk. The pink in the center of the map has the highest risk. The white star denotes the location of today’s quake. Source: INGV, Rome

Besides the difference in the extent of damage and in the number of lives lost, there are several reasons why the two quakes are hard to compare. While today’s quake was followed by several significant aftershocks – one of them reached a magnitude 5.5 – it was not preceded by any noticeable foreshocks. This was different in 2009. In the months before the April 6th quake, the area around L’Aquila was pummeled by hundreds of quakes. Although most of them were small, they were felt by the local population and rattled their nerves. As a consequence, Italy’s government established a commission of experts, who were tasked with evaluating the seismic hazard in relation to this earthquake swarm, which seemed to go on and on.

While these experts were discussing various scenarios, an engineer without any prior knowledge of seismology stole the show. He had observed that the concentration of radon in some groundwater wells had changed during the swarm. Because he had read somewhere that such a change may be an indicator for an upcoming strong earthquake, he predicted in public that a strong quake was imminent. He did not discuss his findings with any seismologist. The commissioners reacted to this surprise announcement by trying to assure the population that such predictions were nonsense – only to be superseded by reality. A few days after the engineer went public, the devastating quake did indeed happen. Because their reaction was deemed completely inadequate, several commissioners were later found guilty of manslaughter.

Before today’s quake, however, nobody had attempted a prediction and no commission was in session to gloss over the seismic risk along the fault lines in the Apennines. In fact, this region of Central Italy is considered to have one of the highest seismic risks in the nation.

One factor that certainly contributed to the widespread damage is the focal depth of today’s quake. The seismologists at the Italian national seismic network computed a focal depth of only 2.5 miles. The closer a quake’s origin is to the Earth’s surface, the stronger the shaking and, hence, the more damage can be expected. (hra125)

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