Risk Assessment Methodology for Cascading Earthquake and Tsunami Impact Applied to the Town of Augusta (Eastern Sicily, Italy)
Abstract
Properly quantified risk assessment products can be of great help in defining suitable mitigation strategies and in building effective emergency management procedures against geohazards impact on cities. In this study, the relevant geohazard is represented by earthquakes and earthquake-generated tsunamis. We propose and describe a methodology that includes all the classical steps in the tsunami hazard-to-risk assessment chain (hazard, vulnerability, damage, exposure, risk) and whose main final products are the quantification of the "Economic loss" (EL) due to the damage suffered by inundated buildings, and of the people exposure and of the number of fatalities ("Human Damage", HD) expected to occur in the inundated area. The methodology is applied to the town of Augusta (eastern Sicily, Italy), that, according to historical and paleotsunami catalogues, suffered the impact of at least 7 tsunamis in the last 4000 years: two of them (1169 and 1693 A.D.) are associated with earthquakes with estimated magnitude larger than 7. We first assess the tsunami hazard numerically in terms of water column height in the inundated area for both near- and far-field earthquake sources by means of a worst-case credible scenario approach. The vulnerability assessment, which is limited to buildings, makes use of a classification based on the buildings' structural characteristics. We propose an extension of the classifications that are based only on tsunami impact to include the possible concomitant effects of the parent earthquake, that for near-field sources can cause damage to a building before it is impacted by the tsunami. The damage is quantified by combining the water column height in correspondence with a given building with its vulnerability classification: this is carried out for both far-field sources, for which the tsunami can be considered the only responsible for the damage, and for near-field earthquakes, for which the cascading effects can be relevant. All the previous steps, combined with detailed information on buildings and on demography, finally allow to quantify EL and HD. We discuss the strengths and limitations of our approach, stressing the result that buildings that do not collapse (partially or completely) can play the role of a possible vertical shelter, complementing existing evacuation plans.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMNH51D0801Z
- Keywords:
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- 4306 Multihazards;
- NATURAL HAZARDS;
- 4333 Disaster risk analysis and assessment;
- NATURAL HAZARDS;
- 4335 Disaster management;
- NATURAL HAZARDS;
- 4339 Disaster mitigation;
- NATURAL HAZARDS