Browsing by Author "Guillier, Bertrand"

Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemRestricted
    Establishing empirical period formula for RC buildings in Lima, Peru: evidence for the impact of both the 1974 Lima earthquake and the application of the Peruvian seismic code on high-rise buildings
    (Seismological Society of America, 2014-12) Guillier, Bertrand; Chatelain, Jean-Luc; Tavera, Hernando; Perfettini, Hugo; Ochoa Zamalloa, Angel Jair; Herrera Puma, Dina Bilha
    The easiest building parameter to determine is the elastic fundamental resonance period, or its inverse, the fundamental frequency, preferentially used in seismological studies. This period/frequency is directly related to the building stiffness and can be linked to external inputs (acceleration, soil response, etc.), internal history (construction material and quality, struc- tural design, seismic history, etc.), and more complicated factors such as soil–structure interaction. This frequency is generally obtained through building modeling for the most recent structures but is much more complicated or even impossible to de- termine for old buildings, the blueprints of which are generally not available.
    Palabras clave:Building codesBuildingsConcrete
  • Thumbnail Image
    ItemRestricted
    Morphology, structure and kinematics of a rainfall controlled slow‐moving Andean landslide, Peru
    (Wiley, 2016-09-15) Zerathe, Swann; Lacroix, Pascal; Jongmans, Denis; Marino, Jersy; Taipe, Edu; Wathelet, Marc; Pari, Walter; Smoll, Lionel Fidel; Norabuena Ortiz, Edmundo; Guillier, Bertrand; Tatard, Lucile
    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.
    Palabras clave:LandslidesLacustrine sedimentsStructural geology