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1.
The high activity level of Hybrid Events (HE) detected beneath the Cayambe volcano since 1989 has been more thoroughly investigated with data from a temporary array. The unusual HE spectral content allows separating a high-frequency signal riding on a low-frequency one, with a probable single source. HEs are interpreted as high frequency VT events, produced by the interaction between magmatic heat and an underground water system fed by thaw water from the summital glacier, which trigger simultaneous low-frequency fluid resonance in the highly fractured adjacent medium. Pure VTs are interpreted as ‘aborted’ HEs occurring probably in the oldest and coldest part of the volcano complex. To cite this article: B. Guillier, J.-L. Chatelain, C. R. Geoscience 338 (2006). 相似文献
2.
Morphology,structure and kinematics of a rainfall controlled slow‐moving Andean landslide,Peru
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Swann Zerathe Pascal Lacroix Denis Jongmans Jersy Marino Edu Taipe Marc Wathelet Walter Pari Lionel Fidel Smoll Edmundo Norabuena Bertrand Guillier Lucile Tatard 《地球表面变化过程与地形》2016,41(11):1477-1493
The large slow‐moving landslide of Maca is located in the upper Colca valley (southern Peru), a region characterized by a well pronounced rainy period, and intense and recurrent sustained seismicity. The landslide, developed in deep lacustrine deposits, has recently accelerated, threatening the Maca village. This work aims at understanding the rupture mechanism and the causes of the recent landslide reactivation/acceleration. We present a multidisciplinary characterization of the Maca landslide that includes: (i) geological and morphological mapping in the field; (ii) remote sensing analysis using an historical aerial photograph of 1955 and the Pléiades satellite images (2013); (iii) global positioning system (GPS) including time‐series of surveys over 13 years, and continuous measurements over 14 months; (iv) a geophysical campaign with deep electrical resistivity tomography profiles acquired across the landslide mass. Our study shows that this 60 Mm3 landslide, which can be classified as a clay/silt compound landslide, moved by 15 m between 2001 and 2014 with a large inter‐annual velocity variation (up to a factor of 500) depending on the rainfall intensity. We suggest that these dramatic changes in velocity are the result of the combination of a threshold mechanism and the short intense rainy season in Peru. This study reveals three main driving factors acting at different timescales: (i) over several decades, the river course has significantly changed, causing the Maca landslide reactivation in the 1980s due to the erosion of its toe; (ii) at the year scale, a minimum amount of rainfall is required to trigger the motion and this amount controls the landslide velocity; (iii) transient changes in slide velocity may occur anytime due to earthquakes. This study particularly highlights the non‐linear behaviour of the motion with rainfall. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
3.
Bertrand Guillier Kuvvet Atakan Jean-Luc Chatelain Jens Havskov Matthias Ohrnberger Fabrizio Cara Anne-Marie Duval Stratos Zacharopoulos Paula Teves-Costa The SESAME Team 《Bulletin of Earthquake Engineering》2008,6(1):3-31
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...). 相似文献
4.
An indication of the soil topmost layer response in Quito (Ecuador) using noise H/V spectral ratio 总被引:1,自引:0,他引:1
P. Guguen J. -L. Chatelain B. Guillier H. Yepes 《Soil Dynamics and Earthquake Engineering》2000,19(2):1073
H/V noise spectral ratio (HVSR), standard spectral ratio (SSR), and receiver functions (RF) techniques have been used in the Quito (Ecuador) urban area to estimate the frequency dependence of soil response. Two amplified frequencies obtained by the HVSR method appear on about 60 sites. Taking into account the most amplified frequency rather than considering only the first amplified frequency, generally associated with the fundamental frequency, we find that iso-frequency curves tightly fit the surface geology. The second amplified frequency is interpreted as the fundamental frequency of the soft thin topmost layer, which in some cases amplifies the surface ground motion more than the rest of the soil column. This hypothesis is further supported by the results provided from the SSR and RF studies at a station located on top of a solid waste landfill, and by a study of known thickness of a waste landfill, using the HVSR method. 相似文献
5.
Leila Djadia Djamel Machane Jean-Luc Chatelain Abdesslam Abtout Rabah Bensalem Mehdi Amine Guemache Bertrand Guillier Amar Boudella El-Hadi Oubaiche 《Environmental Earth Sciences》2010,59(5):1149-1158
Results from geophysical investigations (electrical resistivity, electromagnetic mapping and seismic refraction) on an excavated
cell of the Ouled Fayet (Algiers, Algeria) pilot landfill indicated the presence of an underground runoff and permeable soil
underneath the cell. These results contradict those obtained by a feasibility study, based, however, only on the analysis
of seventy-six 10-m drilling cores. The 1D boreholes information has been proven to be insufficient and to give biased results.
The presence of water at depth is evidenced by lower resistivity, high conductivity anomalies and increase of P-wave velocity.
Thus, to the contrary of what is claimed in the feasibility study, a threat of leachate pollution is real. This study shows
that landfill construction studies cannot give trustful results without geophysical investigations. More specifically, in
Algeria, it is imperative to elaborate a landfill construction code, which should include mandatory geophysical prospecting
and deeper drilling cores. 相似文献
6.
Molnar S. Sirohey A. Assaf J. Bard P.-Y. Castellaro S. Cornou C. Cox B. Guillier B. Hassani B. Kawase H. Matsushima S. Sánchez-Sesma F. J. Yong A. 《Journal of Seismology》2022,26(4):653-685
Journal of Seismology - The single-station microtremor horizontal-to-vertical spectral ratio (MHVSR) method was initially proposed to retrieve the site amplification function and its resonance... 相似文献
7.
Evaluation of the influence of experimental conditions on H/V results from ambient noise recordings 总被引:5,自引:2,他引:3
Jean-Luc Chatelain Bertrand Guillier Fabrizio Cara Anne-Marie Duval Kuvvet Atakan Pierre-Yves Bard 《Bulletin of Earthquake Engineering》2008,6(1):33-74
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. 相似文献
8.
Philippe Guéguen Jean-Luc Chatelain Bertrand Guillier Hugo Yepes Jose Egred 《Soil Dynamics and Earthquake Engineering》1998,17(5):329-334
The 28 March 1996 earthquake (Mw=5.7) produced extensive damage in Pujili, a small town located in the central part of the Inter-Andean valley of Ecuador. Variations in the damage rate of adobe constructions throughout the city let us suppose a ground motion amplification related to site effects. A site effect study using the H/V spectral ratio confirmed the good agreement with geological formations and showed that a second peak in some soil response appears at sites that are located over a zone of alluvial deposits, in the most damaged area of the city. This second peak is in the frequency range 5–7 Hz, close to the natural response of adobe building frequency. Thus, the second peak seems to increase the damage rate of adobe buildings and may be related to superficial alluvial deposits of a river, acting independently of the rest of the soil column. 相似文献
9.
Seismic response of Beirut (Lebanon) buildings: instrumental results from ambient vibrations 总被引:1,自引:1,他引:0
Christelle Salameh Bertrand Guillier Jacques Harb Cécile Cornou Pierre-Yves Bard Christophe Voisin Armand Mariscal 《Bulletin of Earthquake Engineering》2016,14(10):2705-2730
Resonance period is a key parameter in the seismic design of a structure, thus dynamic parameters of buildings in Beirut (Lebanon) were investigated based on ambient vibration method for risk and vulnerability assessment. Lebanon is facing high seismic hazard due to its major faults, combined to a high seismic risk caused by dense urbanization in addition to the lack of a seismic design code implementation. For this study, ambient vibration recordings have been performed on 330 RC buildings, period parameters extracted and statistically analyzed to identify correlations with physical building parameters (height, horizontal dimensions, age) and site characteristics (rock sites or soft sites). The study shows that (1) the building height or number of floors (N) is the primary statistically robust parameter for the estimation of the fundamental period T; (2) the correlation between T and N is linear and site dependent: T ≈ N/23 for rock sites and N/18 for soft sites; (3) the measured damping is inversely proportional to the period: the taller the building the lower is the damping; (4) a significant overestimation of the period exists in current building codes. However part of the large discrepancy with building code recommendations may be due to the very low level of loading. 相似文献
10.