Review article
ASSESSMENT OF SITE EFFECTS USING MICROTREMOR MEASUREMENTS IN VARAŽDIN CITY
Davor Stanko
orcid.org/0000-0003-1829-0862
; Faculty of Geotechnical Engineering, University of Zagreb, Varaždin, Croatia
Stjepan Strelec
; Faculty of Geotechnical Engineering, University of Zagreb, Varaždin, Croatia
Mario Gazdek
; Faculty of Geotechnical Engineering, University of Zagreb, Varaždin, Croatia
Alen Filipović
; Faculty of Geotechnical Engineering, University of Zagreb, Varaždin, Croatia
Nikola Kaniški
; Faculty of Geotechnical Engineering, University of Zagreb, Varaždin, Croatia
Abstract
A local site effect also affects intensity of soil vibration during an earthquake except of magnitude and epicenter distance from earthquake. When seismic wave propagates through soil, it comes to the amplification of seismic ground motion from bedrock to ground surface soil. In the last two decades, microtremor measurements method, e.g. HVSR (Horizontal-to-Vertical Spectral Ratio) has been showed as fast and simple method for assessment of local site effects, i.e. determination of resonant soil frequencies and soil amplification factors. Microseismic noise can be defined as a continuously Earth tremor caused by natural (wind, ocean waves, long
earthquakes, cyclones and anticyclones) and artificial (traffic, industrial machines) sources. In this paper we demonstrate use of
microtremor measurement method for assessment of local site effect in Varaždin city. Given results are compared to the existed boreholes inside and outside the city and a strong correlation have found between geological structure and measured frequencies and
amplifications of local alluvial soil. HVSR method proved to be useful for fast and efficient assessment of resonant soil frequency f0
and soil amplification HVSR(f) = A(f) in an area of low seismicty like Varaždin city. Assessment of local site effects is very important
for urban planning, assessment of seismic danger zones in city area, for aseismic building construction, and also for potential sesimic
evaluation of historical building retrofiting.
Keywords
microtremor; site effects; resonant frequency of soil; amplification factor; urban planning
Hrčak ID:
141044
URI
Publication date:
19.6.2015.
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