The April 2009 Abruzzi, Italy, Earthquake: Impact on Site Seismic Hazard Estimation

At 0132 UTC (0332 local time) on 6 April 2009, a major earthquake (ML = 5.8, Mw = 6.3) occurred a few kilometers southwest of the city of L'Aquila in the Abruzzi region of central Italy (http://earthquake.usgs.gov/eqcenter/eqinthenews/2009/us2009fcaf/). The quake was preceded by a long and often intense seismic sequence, and it was followed by a series of aftershocks. The extensive damage from the major earthquake resulted in about 300 fatalities, 1200 injuries, and 40,000 evacuees, suggesting widespread ground motioneffects and Mercalli-Cancani-Sieberg (MCS) scale intensities of up to level IX (http://portale.ingv.it/ primo-piano-1/news-archive/2009-news/april-6-earthquake/copythe-l-aquila-seismic-sequence-april-2009/view?set_language=en). Such intensity levels correspond to an impact on buildings, in terms of maximum ground horizontal acceleration, as great as 0.6 g, where g is the acceleration of gravity. An acceleration of about 0.6 g actually was measured by accelerometric stations in the L'Aquila valley (http://mceer.buffalo.edu/infoservice/disasters/ground-motion-summary.pdf).