From March to September 2009, a velocimetric network was installed in Narni, central Italy, a village on the top of a limestone ridge. The aim was to investigate local site effects due to the 220-m-high ridge, which is characterized by slopes ranging from 22° to 35°. To investigate amplification without and with a reference site, three stations were installed at the base of the hill and seven at the crest. The network recorded 702 earthquakes, many of them from the 2009 L'Aquila sequence. To determine the dependence of amplification on the morphological features, the spectra were computed for horizontal components rotated into a range of azimuths. Both the ratio of the horizontal-to-vertical-component spectra and the ratio of the spectra at the ridge crest with respect to a reference station at the base of the ridge showed amplification by a factor of ca. 4.5 for frequencies between 4 Hz and 5 Hz. The highest amplifications were seen for the directions of the ground motion perpendicular to the main elongation of the ridge. Finally, considering events with an epicentral distance less than 30 km, empirical ground motion models were calibrated for maximum horizontal peak ground acceleration, velocity and acceleration response spectra (5% damping) up to 1 s, to estimate the site corrective coefficients for topographic amplification. The data show corrective coefficients between 0.35 and 0.48 (log10 scale; amplification, 2.2-3.0) for the spectral ordinates between 0.2 s and 0.3 s

A temporary network of 33 seismic stations was deployed in the area struck by the 6th April 2009, Mw 6.3, L’Aquila earthquake (central Italy), with the aim to investigate the site amplification within the Aterno river Valley. The seismograms of 18 earthquakes recorded by 14 of the 33 stations were used to evaluate the average horizontal to vertical spectral ratio (HVSR) for each site and the standard horizontal spectral ratio (SSR) between a site and a reference station. The obtained results have been compared to the geological and geophysical information in order to explain the resonance frequencies and the amplification levels with respect to surface geology of the valley. The result indicate that there is no uniform pattern of amplification, due to the complex geologic setting, as the thickness and degree of cementation of the deposits is highly variable. As consequence, a large number of the local site response is observed, therefore it is very difficult to elaborate a unique model that can explain such a variability of the amplification

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