An adequate modelling of shaking affecting marginally stable slopes during earthquakes is needed to assess seismic landslide hazard, but it is made difficult by the lack of pertinent instrumental observations and by the complexity showed by slope seismic response. Some advancement on knowledge of seismic response in landslide areas has been recently obtained from new experimental observations. In particular a long term accelerometric monitoring of a landslide-prone slope area in Italy showed examples of amplifications with directivity properties apparently correlated with the directions of local topographic features. Similar phenomena have been also observed in other sites. The recognition of these site effects is important because they can enhance the slope susceptibility to fail under seismic shaking. At present factors controlling directional amplification of slope seismic response are still unclear, and general criterion to distinguish where these phenomena can occur are not available. However some techniques to identify sites affected by seismic response directivity have been successfully experimented. These methods analyse recordings of seismic weak motion and ambient microtremors to reveal preferential directivity of site response in terms of shaking energy and spectral properties. A comparison with recordings obtained during the recent Mw=6.3 earthquake that hit the Abruzzo region in April 2009 confirmed that observations at low energy level can give valid indications also for slope behaviour under stronger shaking.
Amplification and directivity phenomena in the dynamic response of slopes to seismic shaking
DEL GAUDIO, Vincenzo
2009-01-01
Abstract
An adequate modelling of shaking affecting marginally stable slopes during earthquakes is needed to assess seismic landslide hazard, but it is made difficult by the lack of pertinent instrumental observations and by the complexity showed by slope seismic response. Some advancement on knowledge of seismic response in landslide areas has been recently obtained from new experimental observations. In particular a long term accelerometric monitoring of a landslide-prone slope area in Italy showed examples of amplifications with directivity properties apparently correlated with the directions of local topographic features. Similar phenomena have been also observed in other sites. The recognition of these site effects is important because they can enhance the slope susceptibility to fail under seismic shaking. At present factors controlling directional amplification of slope seismic response are still unclear, and general criterion to distinguish where these phenomena can occur are not available. However some techniques to identify sites affected by seismic response directivity have been successfully experimented. These methods analyse recordings of seismic weak motion and ambient microtremors to reveal preferential directivity of site response in terms of shaking energy and spectral properties. A comparison with recordings obtained during the recent Mw=6.3 earthquake that hit the Abruzzo region in April 2009 confirmed that observations at low energy level can give valid indications also for slope behaviour under stronger shaking.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
