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Chatelain, Jean-Luc
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- PublicationOpen AccessSesame Project - Deliverable D08-02 - WP02 H/V technique : experimental conditions - Final report on Measurement Guidelines(2003-07)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;Atakan, Kuvvet; University of Bergen, Norway ;Azzara, RIccardo Mario; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Bard, Pierre-Yves; LGIT, Grenoble, France ;Bonnefoy-Claudet, Sylvette; LGIT, Grenoble, France ;Borges, Antonio; ICTE, Lisbon, Portugal ;Bottger Sorenses, Mathilde; University of Bergen, Norway ;Cara, Fabrizio; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Chatelain, Jean-Luc; LGIT, Grenoble, France ;Cultrera, Giovanna; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Di Giulio, Giuseppe; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Dunand, Francois; LGIT, Grenoble, France ;Duval, Anne-Marie; CETE, Nice, France ;Faeh, Donat; ETHZ, Zurich, Swiss ;Gueguen, Philippe; LGIT, Grenoble, France ;Guillier, Bertrand; LGIT, Grenoble, France ;Ripperger, Johannes; ETHZ, Zurich, Swiss ;Teves-Costa, Paula; ICTE, Lisbon, Portugal ;Vassiliades, Jean-Francois; CETE, Nice, France ;Vidal, Sylvain; CETE, Nice, France ;Wassner, Jochen; ETHZ, Zurich, Swiss; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; In the following we report the final results for WP02-Measurement Guidelines. This work was conducted under the framework of the SESAME Project (Site Effects Assessment Using Ambient Excitations, EC-RGD, Project No. EVG1-CT-2000-00026 SESAME), Task A (H/V technique), Work Package 02 (WP02 – Measurement Guidelines).221 212 - PublicationRestrictedInfluence of instruments on the H/V spectral ratios of ambient vibrations(2008)
; ; ; ; ; ; ; ; ; ;Guillier, B.; LGIT-IRD, Observatoire de Grenoble, BP 53-38041, Grenoble Cedex, France ;Atakan, K.; UiB, Bergen, Norway ;Chatelain, J.-L.; LGIT-IRD, Observatoire de Grenoble, BP 53-38041, Grenoble Cedex, France ;Havskov, J.; UiB, Bergen, Norway ;Ohrnberger, M.; IGUP, Potsdam, Germany ;Cara, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Duval, A.-M.; CETE, Nice, France ;Zacharopoulos, S.; ITSAK, Thessaloniki, Greece ;Teves-Costa, P.; ICTE-UL, Lisbon, Portugal; ; ; ; ; ; ; ; For an optimal analysis of the H/V curve, it appears necessary to check the instrument signal to noise ratio in the studied frequency band, to ensure that the signal from the ground noise is well above the internal noise. We assess the reliability and accuracy of various digitizers, sensors and/or digitizer-sensor couples. Although this study is of general interest for any kind of seismological study, we emphasize the influence of equipment on H/V analysis results. To display the impact of the instrumental part on the H/V behavior, some series of tests have been carried out following a step-by-step procedure: first, the digitizers have been tested in the lab (sensitivity, internal noise...), then the three components sensors, still in the lab, and finally the usual user digitizers-sensors couple in lab and outdoors. In general, the digitizer characteristics, verified during this test, correspond well to the manufacturer specifications, however, depending on the digitizer, the quality of the digitized waveform can be very good to very poor, with variation from a channel to another channel (gain, time difference etc.). It appears very clearly that digitizers need a warming up time before the recording to avoid problems in the low-frequency range. Regarding the sensors, we recommend strongly to avoid the use of “classical” accelerometers (i.e., usual force balance technology). The majority of tested seismometers (broadband and short period, even 4.5 Hz) can be used without problems from 0.4 to 25 Hz. In all cases, the instrumentation should be checked first to verify that it works well for the defined study aim, but also to define its limit of use (frequency, sensitivity...).176 21 - PublicationRestrictedGeopsy: A User-Friendly Open-Source Tool Set for Ambient Vibration Processing(2020)
; ; ; ; ; ; ; ; ; ; ; ; ; Ambient vibrations are nowadays considerably used worldwide for numerous types of engineering applications and scientific research. Geopsy and its companion tools are part of that landscape. Since the first release of the program package in 2005, as outcome of the European Union project Site Effects aSsessment from AMbient noisE, Geopsy has become a mature multiplatform open-source package (released under GNU Public License version 3) that has already been recognized as a reference tool for analyzing ambient vibration data in the context of site characterization studies. The community of users has grown from a core group of researchers up to thousands of seismologists and engineers on every career level and on all continents. The versatility of geopsy allows for the processing of all kinds of data needed in site characterization studies, that is, from single station single trace to three-component array recordings. In all of the aforementioned cases, the steps from field acquisition to the production of publication-ready figures are covered and supported by user-friendly graphical user interfaces or corresponding command-line tools for the automation of the complete processing chain. To avoid black-box usage, a number of lower-level tools guarantee maximum flexibility in accessing and controlling processing results at any stage of the analysis282 5 - PublicationRestrictedEvaluation of the influence of experimental conditions on H/V results from ambient noise recordings(2008)
; ; ; ; ; ; ;Chatelain, J.-L.; IRD-LGIT, BP 53, 38041 Grenoble Cedex 9, France ;Guillier, B.; IRD-LGIT, BP 53, 38041 Grenoble Cedex 9, France ;Cara, F.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma1, Roma, Italia ;Duval, A.-M.; CETE, Nice, France ;Atakan, K.; UiB, Bergen, Norway ;Bard, P.-Y.; LCPC-LGIT, Grenoble, France; ; ; ; ; The H/V-noise technique is now widely used to estimate site effect parameters (fundamental frequency and sometimes the associated soil amplification), and many surveys using this technique have provided convincing results. However, a general agreement on a methodology for data acquisition, data processing and result interpretation has yet to be found. H/V measurements from ambient noise recordings imply both reliability of the results and rapidity of data collection. It is therefore important to understand which experimental conditions (1) influence data quality and reliability, and (2) can help speeding up the recording process. Within the framework of the SESAME European project, a specific task was defined to investigate the reliability of the H/V spectral ratio technique in assessing the site effects. The aim of WP02, one specific Work Package of the SESAME project, is to study the effects of experimental conditions on both stability and reproducibility of H/V results. This study has been conducted in a purely experimental way, by testing the possible influence of various experimental conditions on H/V results both on the frequency peak value and on its amplitude. WP02 results help setting up the experimental conditions under which ambient noise recordings have to be performed in order to provide reproducible, reliable and meaningful H/V results. In this paper we present the results of the WP02 SESAME project concerning the evaluation of the influence of experimental conditions of ambient noise recording on H/V results.196 30