Publication Date:
2017-04-04
Description:
Kyrgyzstan, which is located in the collision zone between the Eurasian
and Indo-Australian lithosphere plates, is prone to large earthquakes as shown by its
historical seismicity. Hence, an increase in the knowledge and awareness by local
authorities and decision makers of the possible consequence of a large earthquake,
based on improved seismic hazard assessments and realistic earthquake risk scenarios,
is mandatory to mitigate the effects of an earthquake. To this regard, the Central Asia
Cross-Border Natural Disaster Prevention (CASCADE) project aims to install a cross-
border seismological and strong motion network in Central Asia and to support
microzonation activities for the capitals of Kyrgyzstan, Uzbekistan, Kazakhstan,
Tajikistan, and Turkmenistan. During the first phase of the project, a temporary
seismological network of 19 stations was installed in the city of Bishkek, the capital
of Kyrgyzstan. Moreover, single-station noise recordings were collected at nearly 200
sites. In this study, the site amplifications occurring in Bishkek are assessed by
analyzing 56 earthquakes extracted from the data streams continuously acquired
by the network, as well as from the single-station noise measurements. A broadband
amplification (starting at ∼0:1 and 0.2 Hz), is shown by the standard spectral ratio
(SSR) results of the stations located within the basin. The reliability of the observed
low-frequency amplification was validated through a time–frequency analysis of
denoised seismograms. Discrepancies between horizontal-to-vertical spectral ratio
and SSR results are due to the large amplification of the vertical component of ground
motion, probably due to the effect of converted waves. The single-station noise results,
once their reliability was assessed by their comparison with the earthquake data, have
been used to produce the first fundamental resonance frequency map for Bishkek,
whose spatial variation shows a good agreement with the presence of an impedance
contrast within the Tertiary sedimentary cover.
Description:
Published
Description:
3068-3082
Description:
4.1. Metodologie sismologiche per l'ingegneria sismica
Description:
JCR Journal
Description:
open
Keywords:
site effects
;
04. Solid Earth::04.06. Seismology::04.06.04. Ground motion
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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