Earthquake and Medieval City: Modern City Connection?

A 5.8-magnitude earthquake that struck northern Italy's Ferrara in 1570--bringing about dozens of deaths, significant city damage, and widespread fleeing--was part of a new study showing that the quake and its aftershocks were part of a tectonic process over thousands of years, which changed the course of the Po River. By the end of the 16th century, Ferrara no longer had a river, as a statement noted.

Livio Sirovich and Franco Pettenati, scientists at the National Institute for Oceanography and Experimental Geophysics in Trieste, Italy, published their new research in Journal of Geophysical Research-Solid Earth.

The researchers used historical data and new modeling techniques to learn that the earthquake was on a fault that lay beneath Po River sediments, about 9 miles north-northeast of Ferrara. The fault is part of the buried front of the northern Apennine Mountains, which has caused uplift of the Po Valley's southern portion over millions of years, the statement said.

The uplift over the past 2,800 years moved the Po River by about 12 miles north, between the towns of Guastalla and Ficarolo, the statement said.

The earthquake was the "straw that broke the camel's back" regarding the river's direction, said the study's authors in the release. The earth movement and aftershocks lifted the valley by about 4 to 6 inches, rerouting the Po River's southern portion to the present location, about 25 miles north of its 1570 location, over ensuing years, according to the statement.

The researchers also learned that the fault that caused the 1570 quake was not the same as the one that caused an Emilia, Italy major earthquake in 2012. Also, that recent earthquake did not switch stress toward the fault that moved so explosively in 1570, which lessens the risk that the 1570 fault will be triggered again, as a release noted.

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