Monday, September 28, 2009

Why Perugia Is At Less Risk Of Earthquakes Than Its Neighbors

Posted by Peter Quennell


See Perugia and you will agree. Any earthquake damage to this truly wonderful town would be a great tragedy in itself.

Here was our previous post. Now an American expert has made public the finding that Perugia is very unusually kind of riding the waves, which explains why it has not seen a major earthquake in 2000 years.

U.S. researchers say they’ve determined some slow-moving faults may help protect some regions of Italy and other parts of the world from earthquakes.

University of Arizona postdoctoral researcher Sigrun Hreinsdottir said until now, geologists thought when a crack between two pieces of the Earth’s crust was at a very gentle slope, there was no movement along that particular fault line.

“This study is the first to show that low-angle normal faults are definitely active,” Hreinsdottir said.

Assistant Professor Richard Bennett, who led the study, said scientists can now “show that the Alto Tiberina fault beneath Perugia is steadily slipping as we speak—fortunately, for Perugia, without producing large earthquakes.”

Perugia is the capital city of Italy’s Umbria region.

Creeping slowly is unusual, Bennett said. Most faults stick, causing strain to build up, and then become unstuck with a big jerk that translates into a big earthquake.

Hreinsdoottir and Bennett say they have shown the gently sloping fault beneath Perugia is moving steadily at the rate of approximately one-tenth of an inch a year.

They said Perugia has not experienced a damaging earthquake in about 2,000 years because the fault is actively slipping and might not be collecting strain.

“To have an earthquake, you have to have strain,” Hreinsdoottir said.  The research appears in the August issue of the journal Geology.


Posted by Peter Quennell on 09/28/09 at 11:19 AM in The wider contextsItalian context


Comments

I suppose Ms. Knox and co. is the most recent earthquake.

Posted by LReik on 09/29/09 at 03:34 PM | #


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