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Crustal Deformation Used to Estimate Earthquake Recurrence in the Apennine Mountains
Seismic hazard assessments require knowledge of the amount of strain accumulated and released along faults. This information can be obtained through measures of crustal deformation and from estimates of strain released by past earthquakes. Over time, the strain released by earthquakes should mirror the tectonic deformation.
Writing in Geophysical Research Letters Dr. Nicola D'Agostino compared the rate of crustal deformation determined using GPS measurements with the strain released by recorded earthquakes in the past approximately 500 years along a 400-kilometer stretch of Italy’s Apennine Mountains. He found these estimates of seismic strain accumulation and release agree well.
On the basis of this analysis, Dr. D'Agostino estimated that the average recurrence interval for magnitude 6.5 and greater earthquakes in the region is about 30 to 75 years. A minimum estimate of unreleased tectonic strain in the last 500 years shows that along about 35% of the Apennine range, enough deformation has occurred to allow the release of an earthquake of such magnitude. The definition of seismic potential for smaller earthquakes is more uncertain, and they remain a significant hazard to the Apennine region.