Résumé: Speleoseismology is the investigation of earthquake records in caves. Traces can be seen in broken speleothems, growth anomalies in speleothems, cave sediment deformation structures, displacements along fractures and bedding plane slip, incasion (rock fall) and co-seismic fault displacements. Where earthquake origins can be proven, these traces constitute important archives of local and even regional earthquake activity. However, other processes that can generate the same or very similar deformation features have to be excluded before cave damage can be interpreted as earthquake induced. Most sensitive and therefore most valuable for the tracing of strong earthquake shocks in caves are long and slender speleothems, such as soda straws, and deposits of well-bedded, water-saturated silty sand infillings, particularly in caves close to the earth's surface. Less easily proven is a co-seismic origin of an incasion and other forms of cave damage. The loads and creep movements of sediment and ice fillings in caves can cause severe damage to speleothems which have been frequently misinterpreted as evidence of earthquakes. For the dating of events in geological archives, it is important to demonstrate that such events happened at approximately the same time, i.e. within the error bars of the dating methods. A robust earthquake explanation for cave damage can only be achieved by the adoption of appropriate methods of direct dating of deformation events in cave archives combined with correlation of events in other geological archives outside caves, such as the deformation of lake and flood-plain deposits, locations of rock falls and active fault displacements

Résumé: A better understanding of heat fluxes and temperature distribution in continental rocks is of great importance for many engineering aspects (tunnelling, mining, geothermal research, etc.). This paper aims at providing a conceptual model of temperature distribution in karst environments which display thermal ‘anomalies’ as compared with other rocks. In temperate regions, water circulation is usually high enough to ‘drain-out’ completely the geothermal heat flux at the bottom of karst systems (phreatic zone). A theoretical approach based on temperature measurements carried out in deep caves and boreholes demonstrates, however, that air circulation can largely dominate water infiltration in the karst vadose zone, which can be as thick as 2000 m. Consequently, temperature gradients within this zone are similar to the lapse rate of humid air (
0.5
C 100 m)1). Yet, this value depends on the regional climatic context and might present some significant variations

Résumé: Solute concentration variations during flood events were investigated in a karst aquifer of the Swiss Jura. Observations were made at the spring, and at the three main subterraneous tributaries feeding the spring. A simple transient flow and transport numerical model was able to reproduce chemographs and hydrographs observed at the spring, as a result of a mixing of the concentration and discharge of the respective tributaries. Sensitivity analysis carried out with the model showed that it is possible to produce chemical variations at the spring even if all tributaries have constant (but different for each of them) solute concentrations. This process is called tributary mixing. The good match between observed and modelled curves indicate that, in the phreatic zone, tributary mixing is probably an important process that shapes spring chemographs. Chemical reactions and other mixing components (e.g. from low permeability volumes) have a limited influence. Dissolution-related (calcium, bicarbonate, specific conductance) and pollution-related parameters (nitrate, chloride, potassium) displayed slightly different behaviours: during moderate flood events, the former showed limited variations compared to the latter. During large flood events, both presented chemographs with significant changes. No significant event water participates in moderate flood events and tributary mixing will be the major process shaping chemographs. Variations are greater for parameters with higher spatial variability (e.g. pollution-related). Whereas for large flood events, the contribution of event water becomes significant and influences the chemographs of all the parameters. As a result, spring water vulnerability to an accidental pollution is low during moderate flood events and under base flow conditions. It strongly increases during large flood events, because event water contributes to the spring discharge. (c) 2006 Elsevier B.V. All rights reserved