The Role of the Water Level in the Assessment of Seismic Vulnerability for the 23 November 1980 Irpinia–Basilicata Earthquake

Davide Forcellini

doi:10.3390/geosciences10060229

Abstract

The seismic vulnerability of structures is closely related to changes in the degree of soil saturation that may cause significant changes in volume and shear strength, and consequently, bearing capacity. This paper aims to consider this issue during the strong earthquake that struck Southern Italy on 23 November 1980 (Ms = 6.9) and affected the Campania and Basilicata regions. Several 3D numerical finite element models were performed in order to consider the effects of soil–structure interaction (SSI) on a representative benchmark structure. In particular, the role of the water level depth is herein considered as one of the most significant parameters to control the shear deformations inside the soil, and thus the performance of the superstructure. Results show the importance of considering the water level for buildings on shallow foundations in terms of settlements, base shear forces and floor displacements.

Highlights

The historical 23 November 1980 Irpinia–Basilicata (Southern Italy) earthquake (Ms = 6.9) showed the importance of assessing seismic risk for Italian communities
After the 23 November 1980 Irpinia–Basilicata earthquake, several contributions considered the various mechanisms of rupture [13,14,15,16,17] and estimated damages [18], which focused on the effects of spectral accelerations [19,20,21] or quantified the consequences [22,23,24], and proposed several models [25,26]. Even with such extended literature, information regarding the level of the water table was not registered; this paper proposes numerical simulations of 3D models with different water levels in order to investigate the role of this parameter on the seismic vulnerability of the structure, which was previously investigated [27]
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Summary

Introduction

Earthquake vulnerability depends on the mechanisms occurring inside the superficial layers that filter the input motion from the bedrock. Many parameters may drive these mechanisms, such as soil properties, bedrock characteristics, layers depth, stratification and water level. Other contributions showed the importance of controlling the water table as a soil improvement [3,4]. The correlation between shallow groundwater levels and liquefaction occurrence is proposed by [5] for the May 2006 earthquake at Yogyakarta (Indonesia). [6] showed the effects of water level on analytical indexes for liquefaction susceptibility, while [7] investigated the effects of water table level during the recent Emilia Romagna earthquake, where the oscillations were shown to be limited to less than 2 m

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Results

Discussion

Conclusion