Thermal anomalies and fluid geochemistry framework in occurrence of the 2000-2001 Nizza Monferrate seismic sequence (northern Italy): Episodic changes in the fault zone heat flow or chemical mixing phenomena?

摘要: Abstract. The paper discusses the correlation between heating of shallow groundwater over a 10 × 20 km wide area close to town Nizza Monferrato (Piemonte Region, Northern Italy) and concomitant local seismic sequences during period August 2000 – July 2001. first sequence started on 21 with Ml = 5.2 earthquake. Within few hours, authorities received calls alerting that temperature rose from 30°C in many wells. Our geochemical experimental data geological-seismotectonic framework do not allow hypothesis simple fluid mixing thermal reservoir Acqui Terme Nizza-Monferrato explain observed anomalies. On other hand, we invoke more complex processes such as frictional heating, mechano-chemistry, fault-valve mechanism, adiabatic decompression hydrogeologically driven heat flow i.e., effects due variations basin-scale permeability field. All these are able transmit surface generate transient incremental better than mass transfer occurring typically when fluids different reservoirs mix.