The need of effective strategies for the prevention and mitigation of damage caused by earthquake-induced landslides has stimulated recent developments of techniques for the assessment of seismic landslide exposure at regional scale. However, for a rational risk management, a crucial element is represented by the time horizon of the hazardous events. A new way to incorporate the time factor in seismic landslide hazard assessment is proposed here. It consists in evaluating the temporal recurrence of seismically-induced slope failure conditions inferred from the Newmarks model: first, by adopting Arias Intensity to quantify seismic shaking, well established methods of seismic hazard assessment are employed to obtain the occurrence probabilities of different levels of seismic shaking in a time interval of interest; then, some empirical relations, based on the Newmarks model, are employed to evaluate the slope critical acceleration ac for which a pre-fixed probability exists that seismic shaking would result in landslide triggering. The obtained ac values represent the minimum slope resistance required to keep the probability of seismic landslide triggering within the pre-fixed value. Therefore, the space distribution of the calculated ac values can be promptly compared with the actual in-situ ac values of specific slopes in order to estimate whether these slopes have a significant probability to fail under seismic action in the future. An example of this approach, applied to an area of the Southern Italy (Daunia region), shows that the introduction of the time factor modifies significantly the representation of spatial hazard and allows to evaluate the relevance of seismicity as landslide triggering agent.
An approach to time probabilistic evaluation of seismically-induced landslide hazard.
2003
Abstract
The need of effective strategies for the prevention and mitigation of damage caused by earthquake-induced landslides has stimulated recent developments of techniques for the assessment of seismic landslide exposure at regional scale. However, for a rational risk management, a crucial element is represented by the time horizon of the hazardous events. A new way to incorporate the time factor in seismic landslide hazard assessment is proposed here. It consists in evaluating the temporal recurrence of seismically-induced slope failure conditions inferred from the Newmarks model: first, by adopting Arias Intensity to quantify seismic shaking, well established methods of seismic hazard assessment are employed to obtain the occurrence probabilities of different levels of seismic shaking in a time interval of interest; then, some empirical relations, based on the Newmarks model, are employed to evaluate the slope critical acceleration ac for which a pre-fixed probability exists that seismic shaking would result in landslide triggering. The obtained ac values represent the minimum slope resistance required to keep the probability of seismic landslide triggering within the pre-fixed value. Therefore, the space distribution of the calculated ac values can be promptly compared with the actual in-situ ac values of specific slopes in order to estimate whether these slopes have a significant probability to fail under seismic action in the future. An example of this approach, applied to an area of the Southern Italy (Daunia region), shows that the introduction of the time factor modifies significantly the representation of spatial hazard and allows to evaluate the relevance of seismicity as landslide triggering agent.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
