11Earthquake early warning systems (EEWSs) that rapidly trigger risk-reduction actions after a 12 potentially-damaging earthquake is detected are an attractive tool to reduce seismic losses. One 13 brake on their implementation in practice is the difficulty in setting the threshold required to trigger 14 pre-defined actions: set the level too high and the action is not triggered before potentially-15 damaging shaking occurs and set the level too low and the action is triggered too readily. Balancing 16 these conflicting requirements of an EEWS requires a consideration of the preferences of its 17 potential end users. In this article a framework to define these preferences, as part of a participatory 18 decision making procedure, is presented. An aspect of this framework is illustrated for a hypothetical 19 toll bridge in a seismically-active region, where the bridge owners wish to balance the risk to people 20 crossing the bridge with the loss of toll revenue and additional travel costs in case of bridge closure. 21Multi-Attribute Utility Theory (MAUT) is used to constrain the trigger threshold for four owners with 22 different preferences. We find that MAUT is an appealing and transparent way of aiding the 23 potentially controversial decision of what level of risk to accept in EEW. 24

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A new marine volcano is erupting offshore Mayotte since May 2018, generating numerous earthquakes. The population felt many of them and the stronger shaking of the ongoing sequence caused slight damage to buildings. Historical records also confirm that damaging earthquakes had occurred in the past in this region. Seismic damage scenarios are a key tool for supporting the decision-making process, the preparedness, and for designing appropriate emergency responses. This paper provides the outcomes of a work consisting in improving the seismic risk assessment as a part of disaster risk governance and exposes the scientific background of this workflow. It illustrates its use with two earthquakes. Related post-seismic surveys provide observations that are useful to check the validity of the reference dataset. The paper also discusses the main characteristics of the rapid loss assessment tool that has been developed to provide operational information for crisis management.

Abstract. The article reviews the results of many commercial or research tests carried out in CSTB on middle size concrete slabs. They concern 22 concrete slabs, made of normal and high strength concrete, for a rather wide range of thickness and compressive strength classes. Test procedures and a synthesis of main results are presented in order to provide deeper understanding of near-reality conditions of concrete structures. The tests concerned both new and existing tunnels. Results are detailed in relation with main parameters that are identified as impacting spalling in previous studies, such as concrete composition, concrete properties and specimen size.

Abstract.A comparative analysis of the spalling of (a) cores made of 3 concrete mixes embedded into 3 slabs made of the 3 same concrete mixes; and (b) 3 reference slabs made again of the same 3 concrete mixes has been made. Samples have been exposed to the French Increased HydroCarbon temperature curve. Results confirm that concrete spalling phenomena is not only related to the material properties. Concrete spalling is also very much influenced by the geometry of the samples.