Publication Date:
2017-04-04
Description:
In this work, the results of a quick microtremor survey performed in the municipalities situated in
the epicentre area of the Ml 5.2 2004 Salo` earthquake (North Italy) are presented. The aim of this
study is to understand if the large amount of damage caused by the event (about 215 million euros
only in the areas near to the epicenter) is correlated more to the local surface geology conditions or
to the vulnerability of ancient Italian historical centers.
A preliminary seismic zonation was carried out in 5 villages including about 30 measurements
of microtremors analyzed by the Nakamura technique (hereinafter HVNR). The points of measurement
were carefully selected considering sites located both near damaged buildings and over
different local geology conditions (alluvium deposits, fluvial-glacial deposits, debris fans and
rock). In order to strengthen the HVNR results and to evaluate the reliability of the Nakamura
analysis, a comparison with spectral ratios calculated on earthquakes (hereinafter HVSR) recorded
at the strong motion station of Vobarno was made. In general, the outcomes of the survey highlight
a possible correlation between local geology conditions and ground motion amplification for
different frequency bands. In order to check if this evidence is linked with the damage, a series
of macroseismic intensity values were collected for different zones of the investigated area, and a
nonparametric correlation approach was used to establish a possible correlation between damage
and ground motion amplification for selected frequency bands. The results show, from a statistical
point of view, that in the area surrounding the epicenter of the November 24, 2004 mainshock, the
damage pattern is not strongly dependent upon the local surface geology but more correlated to the
low quality of the civil structures present in the area, including old buildings of the last century.
Description:
Published
Description:
1029-1046
Description:
1.1. TTC - Monitoraggio sismico del territorio nazionale
Description:
3.1. Fisica dei terremoti
Description:
JCR Journal
Description:
open
Keywords:
Salo` Earthquake; Local Surface Geology; HV Spectral Ratios; Nonparametric
;
04. Solid Earth::04.01. Earth Interior::04.01.99. General or miscellaneous
;
04. Solid Earth::04.02. Exploration geophysics::04.02.06. Seismic methods
;
04. Solid Earth::04.02. Exploration geophysics::04.02.07. Instruments and techniques
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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