Why did the Colosseum only half collapse? Due to an earthquake

L'asymmetry of the profile of the Colosseum it is one of the most recognizable characteristics of the most famous amphitheater Roman of the world. Of course it wasn't always like this: the collapse of part of the upper arches depended above all on a earthquake occurred in 1349. But let's take it slow.

After the definitive abandonment of the structure during 6th centurythe Colosseum has undergone a progressive state of decay, like many other buildings of ancient Rome. Furthermore, over the centuries, the eternal city has undergone various earthquakes which affected the stability of the abandoned structures.

The earthquake of 1349in particular, was one of the most intense and caused the failure from the upper arches of the southern side of the Colosseum. The amphitheater, in fact, stands on the border between two different types of terrain: one more stable and one less stable and over time the arches that stood on the most soft part of the ground paid the price.

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If we go into a little more detail about this aspect, the Colosseum was partially built where a pond semi-artificial pertaining to Domus Aureathe enormous private residence of the emperor Nero (37-68). The soil in the area was therefore particularly soft because it was made up of river sediments. The northern part of the Colosseum, however, rested mainly on volcanic rocks, which were decidedly more stable.

The current bare structure of the amphitheater, on the other hand, does not depend only on the earthquake of 1349. latest games inside they were held in the 6th centuryat the time of the domination of the Ostrogoths of Theodoric (454-526). In fact, with the ever-increasing spread of the Christian religion, games became increasingly out of fashion.

The devastation caused by Greco-Gothic war (535-553) definitively brought the city of Rome to its knees, and the ancient monuments, including the Colosseum, were abandoned and used as quarries material to be reused. During the Middle Ages, numerous Roman churches and palaces were built with building materials obtained from the spoils of structures such as the amphitheater.

In the'847 a particularly violent seismic event, with its epicenter in the current area between Campania and Molise, also hit the eternal city causing various damages, including a first failure of the southern side of the Colosseum. The structure did not collapse completely, but the stability was compromised, precisely because of the type of soil on which part of the amphitheater stands.

The definitive collapse of the two upper southern arches, as already mentioned, occurred on the occasion of the great earthquake of 1349. This event was one seismic swarm with several epicenters between southern Lazio and Abruzzo, which caused very serious damage and thousands of victims. At the time, Italy was also devastated by the first major epidemic of plague, which further contributed to bringing Rome to its knees after the earthquake. The great poet Francesco Petrarca (1304-1374) said:

Rome was shaken by an unusual tremor, so seriously that nothing similar has ever happened since its foundation, which dates back over two thousand years ago.

The event was very traumatic for the people of the time, and contributed to giving the largest amphitheater in the world the asymmetric profile that we all know.

INGV Did you know? Why did the Colosseum half collapse?