By Jonathan P. Stewart, Giuseppe Di Capua, Robert E. Kayen, D. Scott Kieffer, Edward Button, Giovanna Biscontin, Giuseppe Scasserra and Giuseppe Lanzo, Paolo Tommasi and Alessandro Pagliaroli, Francesco Silvestri and Anna d’Onofrio, Crescenzo Violante, Armando Lucio Simonelli, Rodolfo Puglia, George Mylonakis, George Athanasopoulos, and Vasileios Vlachakis.
September 2009, Geotechnical Extreme Events Reconnaissance.
This report presents the GEER findings. Following this in troduction, Chapter 2 describes the geologic and tectonic setting, moment tensor solutions for the mainshock and several triggered events, analysis of aftershock patterns, and analysis of GPS and InSAR data. Included in Chapter 2 is a preliminary model of the ruptured fault. Chapter 3 describes the ground motions recorded during the mainshock by a digital instrument array. Metadata associated with the recordings is presented, trends in the recorded ground motions are presented, and preliminary comparisons to ground motion prediction equations are made. Chapter 4 presents damage patterns, both within L’Aquila and through comparisons of damage intensities in adjacent villages with similar construction. The results provide valuable in sights into possible site effects on ground motion in regions where recordings are not available. Chapter 5 presents our findings on ground failure, defined as permanent ground deformations induced by the earthquake. Observed ground failure included several rockfalls, seismic compression of fill materials, and apparent strength loss of soil materials leading to inward movement of the banks of a lake. Chapter 6 reviews the performance of earth dams and earth retaining structures, both of which generally performed well.
