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Seismic Geohazards in Italy: Seismic Geohazards in Italy: An Integrated Geotechnical Earthquake Hazard Assessment Map

Description: 

The study presents an integrated approach to assess three co-seismic geo-hazards: site amplification, liquefaction, and landslides for Italy. The novelty of the approach lies in the construction of 30m x 30m geotechnical spatial grids by adopting a systematic framework, considering the local site response characteristics. The results are discussed in terms of three individual maps: time-averaged shear wave velocity to 30m depth (Vs30), liquefaction, and landslide susceptibilities. Due diligence is given to assess the pertinent hazards for major areas viz. Central Apennines, Southern Italy, Sicily, and the Adriatic Coast. The study also focuses on Northern Italy where the supplementary risks viz. liquefaction and lateral spreading were widely observed post the 2012 Emilia Romagna sequence. We present a novel Vs30 map based on constraining Vs30 observations within multiple secondary parameters such as surficial geology and Multi-Resolution Valley Bottom Flatness (MrVBF) for unconsolidated geology units. The improvements result in a reduction of around 15 – 30% in residual standard deviation in Holocene depositions. A matrix of multidisciplinary datasets that includes geological, hydrological, geotechnical, and terrain data is used to assess the liquefaction susceptibility of Italy. The results provide both lateral and vertical displacements which are further validated using historical observations in Italy. Earthquake-induced landslide hazard assessment is carried out using a bi-variate statistical model of Landslide Susceptibility Zonation (LSZ), augmented with a multi-criteria structured decision technique. Four landslide controlling parameters: geological units, slope angle, slope roughness, and Peak Ground Acceleration are considered to produce an LSZ map for 5 historical earthquake events. The resultant geotechnical site hazard maps provide an exhaustive representation of local site effects and coseismic instabilities in cognizance of seismic risk. The study offers valuable insights for establishing a framework for disaster risk reduction.

Session: Regional-Scale Hazard, Risk and Loss Assessments [Poster Session]

Type: Poster

Date: 5/3/2024

Presentation Time: 08:00 AM (local time)

Presenting Author: Devjyoti

Student Presenter: No

Invited Presentation: 

Authors