GNGTS 2016 - Atti del 35° Convegno Nazionale

GNGTS 2016 S essione A matrice 29 Fig. 2 – Upper panel - a, b) Images taken from the 3D reconstruction of the San Giovanni Battista Church carried out by terrestrial laser scanning (TLS); the triangles indicate the locations of the seismic stations. Lower panel) Preliminary results of the spectral ratios on ambient noise (HVNSR) for each seismic station installed on the building. In Fig. 1, the HVSNR calculated on the base of four hours recordings, selected between daytime and nighttime, are given for all investigated sites. The figure shows a relevant variability of the amplification frequencies from left to right side of the Tronto River. At bottom valley (ACS02 station), where is the contact between travertine and Bisciaro, the spectral ratio shows relevant amplification for frequencies greater than 10Hz. Instead, for the other stations the HVNSRs show amplifications on variable frequency ranges depending on the stratigraphic sequence; however, these frequencies are compatible with those of the built up structures. With reference to the stations located in the San Giovanni Battista Church, the HVNSRs are shown in Fig. 2. In the upper panel of the same figure are reported two images of the preliminary 3D model, that has been reconstructed through data carried out by terrestrial laser scanning and aerial photographic surveys. On the pictures the location of the stations is given. Analyzing the response of the bell tower and the church windows, we find HVSR greater than 4 for frequency ranges compatible with that obtained for the reference station (ACS01), that has been installed in the church garden. Acknowledgements. The authors are grateful to citizens, public administrators and priests of Acquasanta Terme for their support during the deployment of the activities. We also thank the firefighters, who provided the technical support for the installation of the seismic stations on the church. This work has been possible thanks to the instrumentation funded by Ministry of Education, University and Research under the research project PON01-02710 “MASSIMO”. References Costanzo, A.; Minasi, M.; Casula, G.; Musacchio, M.; Buongiorno, M.F. (2015) Combined Use of Terrestrial Laser Scanning and IR Thermography Applied to a Historical Building. Sensors 2015, 15, 194-213. doi:10.3390/ s150100194. Konno, K., and Ohmachi T. (1998). Ground-motion characteristics estimated from spectral ratio between horizontal and vertical components of microtremor, B. Seismol. Soc. Am., 88, 228-241. Nakamura, Y. (1989). A method for dynamic characteristics estimation of subsurface using microtremors and the ground surface, Q. Rept. RTRI Japan, 30, 25-33 SESAME (2004). Guidelines for the implementation of the H/V spectral ratio technique on ambient vibrations- measurements, processing and interpretations. SESAME European research project EVG1-CT-2000-00026, deliverable D23.12, http://sesame-fp5.obs.ujfgrenoble.fr