Quake of 6.6M Rocks Norcia, St Benedict Monastery Destroyed, Why Italy Again?

italian earthquake again

italian earthquake again

Today, October 30, 2016, a massive earthquake measuring 6.6 north of Norcia, Italy, occurred as the result of shallow normal faulting on a NW-SE oriented fault in the Central Apennines, said USGS.

Two months ago, a major earthquake killed almost 300 people and destroyed several towns in Italy with aftershocks recorded last week.

People have been evacuated after last week’s quakes and deaths are likely to be less this time. Tremors were felt even in the capital Rome, and even far away town like Venice in the north.

The US Geological Survey said the epicentre is 68km south-east of the regional centre of Perugia near Norcia.The Basilica of St Benedict in the vicinity was destroyed by the earthquake.

In a statement, the monks said: “The monks are all safe, but our hearts go immediately to those affected, and the priests of the monastery are searching for any who may need the Last Rites.” Norcia is known as the birthplace of St Benedict.

The October 30, 2016 event is the largest event in an on-going sequence of damaging earthquakes that include:

  • the August 24, 2016, M 6.2 central Italy (Amatrice) earthquake which caused approximately 300 fatalities, and severely damaged the town of Amatrice.
  • The October 26, 2016, M 6.1 central Italy earthquake, which, at the time of writing, is not known to have caused any fatalities. This M 6.1 event was preceded by a M 5.5 earthquake, several hours earlier.

Since the August 24, 2016 earthquake, the USGS has reported 41 events of M 4.0 and larger, including a M 5.6 earthquake within an hour of the August 24 shock, and the two large events on October 26 – an M 5.5 event at 17:10 UTC, and the M 6.1 earthquake at 19:18 UTC. Both October 26 events are at the northern end of the aftershock sequence of the M 6.2 August 24 earthquake; the October 26, M 6.1 event is about 30 km northwest of the August 24, M 6.2 earthquake, and thus may reflect triggered failure of an adjacent fault or fault segment. The October 30, M 6.6 event is between the two prior large earthquakes, approximately 10 km southeast of the October 26, M 6.1 event.

The Apennines is a mountain range that runs from the Gulf of Taranto in the south to the southern edge of the Po basin in northern Italy. Geologically, the Apennines is largely an accretionary wedge formed as a consequence of subduction. This region is tectonically and geologically complex, involving subduction of the Adria micro-plate beneath Eurasia and the Apennines from east to west, continental collision between the Eurasia and Nubia (Africa) plates building the Alpine mountain belt further to the north, and the opening of the Tyrrhenian basin to the west (the latter of which is in turn related to Adria subduction and eastward trench migration).

The October 26, 2016 normal faulting earthquake is an intraplate event, an expression of the east-west extensional tectonics that now dominate along the Apennine belt.While related to the previous seismicity, the larger size of this earthquake implies it has ruptured an independent fault patch that had not slipped as part of preceding earthquakes.

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