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Mapping the Seismic Bedrock of the Po Plain (Italy) through Ambient‐Vibration Monitoring
Author(s)
Language
English
Obiettivo Specifico
4T. Sismologia, geofisica e geologia per l'ingegneria sismica
Status
Published
JCR Journal
JCR Journal
Peer review journal
Yes
Title of the book
Issue/vol(year)
/109 (2019)
Pages (printed)
164-177
Issued date
2019
Abstract
In earthquake engineering, “engineering bedrock” is regarded as a stiff
material (i.e., rock or rock-like geological formation) that is characterized by a shearwave
velocity greater than a target value (e.g., 800 m=s; current Italian and European
seismic codes). In the case of deep basins, the identification of engineering bedrock is
problematic, because it can lie well below the penetration depth of most common
prospecting methods (i.e., a few tens of meters). Moreover, the depth of engineering
bedrock might not represent an effective proxy of the sedimentary thickness responsible
for site amplification. The Po Plain sedimentary basin (northern Italy) is one of
the deepest and widest worldwide, and it presents such problems. The aim of this work
is to estimate the sedimentary thickness responsible for ground-motion amplification
at medium and long periods in the Po Plain. Passive seismic prospecting methods
based on ambient-vibration measurements using single-station and array configurations
were considered to map “seismic bedrock” depth. This corresponds to a marked
seismic impedance contrast where the shear-wave velocity approached, or exceeded,
800 m=s. In the latter case, seismic and engineering bedrocks coincided. Our mapping
will be useful for future site response assessments, numerical modeling of seismicwave
propagation, dynamic ground response analyses, and site-specific seismic hazard
evaluation at the basin scale.
material (i.e., rock or rock-like geological formation) that is characterized by a shearwave
velocity greater than a target value (e.g., 800 m=s; current Italian and European
seismic codes). In the case of deep basins, the identification of engineering bedrock is
problematic, because it can lie well below the penetration depth of most common
prospecting methods (i.e., a few tens of meters). Moreover, the depth of engineering
bedrock might not represent an effective proxy of the sedimentary thickness responsible
for site amplification. The Po Plain sedimentary basin (northern Italy) is one of
the deepest and widest worldwide, and it presents such problems. The aim of this work
is to estimate the sedimentary thickness responsible for ground-motion amplification
at medium and long periods in the Po Plain. Passive seismic prospecting methods
based on ambient-vibration measurements using single-station and array configurations
were considered to map “seismic bedrock” depth. This corresponds to a marked
seismic impedance contrast where the shear-wave velocity approached, or exceeded,
800 m=s. In the latter case, seismic and engineering bedrocks coincided. Our mapping
will be useful for future site response assessments, numerical modeling of seismicwave
propagation, dynamic ground response analyses, and site-specific seismic hazard
evaluation at the basin scale.
Type
article
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BSSA-2018193_ONLINE.pdf
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5.48 MB
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