On October 31, 2002, a ML=5.5 earthquake struck the Molise region in Southern Italy. The strongly non-uniform damage distribution observed in the town of San Giuliano di Puglia suggested that site amplification significantly affected the seismic response of the area. Soon after the earthquake, a seismic microzonation study was undertaken on the basis of a detailed geotechnical investigation of the subsoil, including field and laboratory standard and advanced tests. The main geotechnical formations identified in the area consisted of a soft rock formation (flysch) and a deep layer of marly clays. Several aftershocks were recorded by two temporary accelerometric stations located in the ancient and recent zones of the town, on the flysch outcrop and the fine-grained soil respectively. The field and laboratory experimental data allowed the definition of the geotechnical model of the subsoil. The analysis of a deep electric tomography and the frequency content of the aftershocks indicated a thickness of about 300 m for the marly clay formation beneath the accelerometric station in the recent part of the town, but a full description of the bedrock geometry has been not yet achieved. To envisage a more reliable definition of the subsoil model, the results of 2D seismic response analyses carried out referring to different hypotheses were compared to the peak amplitudes and frequency contents recorded during the aftershocks.
Ground motion amplification in S. Giuliano di Puglia (Southern Italy) during the 2002 Molise earthquake
PAGLIAROLI, Alessandro;
2007-01-01
Abstract
On October 31, 2002, a ML=5.5 earthquake struck the Molise region in Southern Italy. The strongly non-uniform damage distribution observed in the town of San Giuliano di Puglia suggested that site amplification significantly affected the seismic response of the area. Soon after the earthquake, a seismic microzonation study was undertaken on the basis of a detailed geotechnical investigation of the subsoil, including field and laboratory standard and advanced tests. The main geotechnical formations identified in the area consisted of a soft rock formation (flysch) and a deep layer of marly clays. Several aftershocks were recorded by two temporary accelerometric stations located in the ancient and recent zones of the town, on the flysch outcrop and the fine-grained soil respectively. The field and laboratory experimental data allowed the definition of the geotechnical model of the subsoil. The analysis of a deep electric tomography and the frequency content of the aftershocks indicated a thickness of about 300 m for the marly clay formation beneath the accelerometric station in the recent part of the town, but a full description of the bedrock geometry has been not yet achieved. To envisage a more reliable definition of the subsoil model, the results of 2D seismic response analyses carried out referring to different hypotheses were compared to the peak amplitudes and frequency contents recorded during the aftershocks.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
